Local Voice Data Processing

ABSTRACT

Example techniques relate to local voice control in a media playback system. A satellite device (e.g., a playback device or microcontroller unit) may be configured to recognize a local set of keywords in voice inputs including context specific keywords (e.g., for controlling an associated smart device) as well as keywords corresponding to a subset of media playback commands for controlling playback devices in the media playback system. The satellite device may fall back to a hub device (e.g., a playback device) configured to recognize a more extensive set of keywords. In some examples, either device may fall back to the cloud for processing of other voice inputs.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. § 119 of U.S. provisional patent Application No. 62/986,675, filed on Jan. 31, 2020, entitled “Local Voice Data Processing via Extensible Playback Device,” which is incorporated herein by reference in its entirety.

FIELD OF THE DISCLOSURE

The present technology relates to consumer goods and, more particularly, to methods, systems, products, features, services, and other elements directed to voice-assisted control of media playback systems or some aspect thereof.

BACKGROUND

Options for accessing and listening to digital audio in an out-loud setting were limited until in 2002, when SONOS, Inc. began development of a new type of playback system. Sonos then filed one of its first patent applications in 2003, entitled “Method for Synchronizing Audio Playback between Multiple Networked Devices,” and began offering its first media playback systems for sale in 2005. The Sonos Wireless Home Sound System enables people to experience music from many sources via one or more networked playback devices. Through a software control application installed on a controller (e.g., smartphone, tablet, computer, voice input device), one can play what she wants in any room having a networked playback device. Media content (e.g., songs, podcasts, video sound) can be streamed to playback devices such that each room with a playback device can play back corresponding different media content. In addition, rooms can be grouped together for synchronous playback of the same media content, and/or the same media content can be heard in all rooms synchronously.

BRIEF DESCRIPTION OF THE DRAWINGS

Features, aspects, and advantages of the presently disclosed technology may be better understood with regard to the following description, appended claims, and accompanying drawings where:

Features, aspects, and advantages of the presently disclosed technology may be better understood with regard to the following description, appended claims, and accompanying drawings, as listed below. A person skilled in the relevant art will understand that the features shown in the drawings are for purposes of illustrations, and variations, including different and/or additional features and arrangements thereof, are possible.

FIG. 1A is a partial cutaway view of an environment having a media playback system configured in accordance with aspects of the disclosed technology.

FIG. 1B is a schematic diagram of the media playback system of FIG. 1A and one or more networks.

FIG. 2A is a functional block diagram of an example playback device.

FIG. 2B is an isometric diagram of an example housing of the playback device of FIG. 2A.

FIG. 2C is a diagram of an example voice input.

FIG. 2D is a graph depicting an example sound specimen in accordance with aspects of the disclosure.

FIGS. 3A, 3B, 3C, 3D and 3E are diagrams showing example playback device configurations in accordance with aspects of the disclosure.

FIG. 4 is a functional block diagram of an example controller device in accordance with aspects of the disclosure.

FIGS. 5A and 5B are controller interfaces in accordance with aspects of the disclosure.

FIG. 6 is a message flow diagram of a media playback system.

FIG. 7A is a functional block diagram of an example network microphone device.

FIG. 7B is an isometric diagram of the example network microphone device.

FIG. 7C is a functional block diagram of certain components of the example network microphone device in accordance with aspects of the disclosure.

FIG. 8 is a schematic diagram illustrating an example media playback system and cloud network in accordance with aspects of the disclosure.

FIGS. 9A, 9B, 9C, and 9D show exemplary output of an example NMD configured in accordance with aspects of the disclosure.

FIG. 10A is a schematic diagram of example voice analysis components of an audio front-end of a satellite playback device in accordance with aspects of the disclosure.

FIG. 10B is a schematic diagram of an example media playback system including a hub device and multiple satellite devices in accordance with aspects of the disclosure.

FIG. 10C is a schematic diagram of example voice analysis components of a hub device in accordance with aspects of the disclosure.

FIG. 10D is a schematic diagram illustrating exemplary cloud fallback in accordance with aspects of the disclosure.

FIG. 10E is a schematic diagram illustrating an embodiment of a media playback system with one or more first playback devices operating as respective satellite devices and a second playback device operating as a hub device in accordance with aspects of the disclosure.

FIG. 10F is a schematic diagram illustrating an embodiment of a media playback system with one or more IOT devices operating as respective satellite devices and a second playback device operating as a hub device in accordance with aspects of the disclosure.

FIGS. 11A and 11B are an example method in accordance with aspects of the disclosure.

The drawings are for purposes of illustrating example embodiments, but it should be understood that the inventions are not limited to the arrangements and instrumentality shown in the drawings. In the drawings, identical reference numbers identify at least generally similar elements. To facilitate the discussion of any particular element, the most significant digit or digits of any reference number refers to the Figure in which that element is first introduced. For example, element 103 a is first introduced and discussed with reference to FIG. 1A.

DETAILED DESCRIPTION I. Overview

Exemplary techniques relate to a media playback system including one or more first playback devices (or satellites) and a hub device (e.g., a second playback device). Relative to the first playback devices, the hub device may be a “plus” device having increased processing power and memory for local spoken language understanding (SLU) of a certain class of voice commands (e.g., media playback) or voice commands generally.

The satellites may include networked microphone device (“NMD”) components such as audio front-end components and on-board voice analysis components. The audio front-end component may include a microphone array to detect voice utterances as well as a spatial processor, an acoustic echo canceller (AEC), and/or other components for processing and filtering detected sound. The voice analysis components may include a wake word detector.

NMDs typically rely on the cloud for natural language understanding, but some NMDs may support local voice processing. Generally, cloud-based VAS(s) are relatively more capable than local (“on-device”) voice input engines. In particular, in contrast to a natural language unit (NLU) implemented in one or more cloud servers that is capable of recognizing a wide variety of voice inputs, it is generally impracticable for local NLUs to recognize voice inputs at the level of scale of a cloud-based NLU. For example, a local NLU implemented by an NMD may be capable of recognizing a relatively smaller library of keywords (e.g., 10,000 words and phrases). Further, the cloud-based VAS may support additional features relative to a local NLU, such as the ability to support a greater breath of features at the same time.

On the other hand, some users are apprehensive of sending their voice data to a cloud-based VAS for privacy reasons. One possible advantage of a processing voice inputs via a local NLU is increased privacy. By processing voice utterances locally, a user may avoid transmitting voice recordings to the cloud (e.g., to servers of a voice assistant service). Further, in some implementations, the NMD may use a local area network to discover playback devices and/or smart devices connected to the network, which may avoid providing personal data relating to a user's home to the cloud. Also, the user's preferences and customizations may remain local to the NMD(s) in the household, perhaps only using the cloud as an optional backup. Accordingly, some users might not enable processing via a cloud-based VAS and instead rely on the local voice input pipeline.

In accordance with aspects of the disclosure, the satellites may be configurable in one of two modes of operation related to voice input processing. In a first mode of operation, the satellites are configured to forward a voice utterance to a remote voice input processor, such as a cloud server, upon detecting a wake word in a voice input. In contrast, when a hub device is present, the satellites switch to operating in a second mode of operation. While in the second mode, the satellites are configured to forward a voice utterance to the hub device rather than to the cloud. In some examples, the hub device may be configured forward a voice utterance to the cloud in certain cases (e.g., when its permitted to by the user and when it determines that it is unable to process the voice utterance locally).

In comparison with the satellites, the hub device includes more relatively more sophisticated voice analysis components, such as an ASR (automatic speech recognition) component and a language modelling and understanding component (“NLU”). Using these components, the hub device performs local spoken language understanding (SLU) of a certain class of voice commands (e.g., media playback) or voice commands generally. Since the processing is local on the hub device, the voice data is not sent to the cloud, which may enhance user privacy. Moreover, since the hub device is able to process voice inputs for a number of satellites, adding one hub device to a media playback system can upgrade privacy (by keeping voice data local) for all voice-capable satellites in their system.

In another example of a hub and satellites system, example systems may include one or more microcontroller units (MCUs) as satellites with a playback device operating as a hub. The MCUs may implement NMD components for detection of a target set of keywords. These keywords may correspond to media playback system commands (e.g., a subset of media playback system commands supported by the media playback system), as well as other context specific keywords. For instance, an MCU implemented in a smart appliance may support smart appliance commands (e.g., in addition to the media playback system commands. The hub may also include NMD components for processing a larger set of media playback system commands (e.g., a superset of the media playback system commands supported by the MCUs).

In examples, when a satellite captures a voice input, the satellite may attempt to process the voice input locally. If the satellite is unable to process the voice input locally (e.g., because the voice input includes keywords that the satellite is not configured to recognize, given its relatively limited processing capability and memory), the satellite can fall back to a more capable device. For instance, satellite may fall back to the hub device (e.g., while operating in the second mode) or may fall back to the cloud (e.g., while operating in the first mode). Other examples are possible as well.

While some embodiments described herein may refer to functions performed by given actors, such as “users” and/or other entities, it should be understood that this description is for purposes of explanation only. The claims should not be interpreted to require action by any such example actor unless explicitly required by the language of the claims themselves.

Moreover, some functions are described herein as being performed “based on” or “in response to” another element or function. “Based on” should be understood that one element or function is related to another function or element. “In response to” should be understood that one element or function is a necessary result of another function or element. For the sake of brevity, functions are generally described as being based on another function when a functional link exists; however, such disclosure should be understood as disclosing either type of functional relationship.

II. Example Operation Environment

FIGS. 1A and 1B illustrate an example configuration of a media playback system 100 (or “MPS 100”) in which one or more embodiments disclosed herein may be implemented. Referring first to FIG. 1A, the MPS 100 as shown is associated with an example home environment having a plurality of rooms and spaces, which may be collectively referred to as a “home environment,” “smart home,” or “environment 101.” The environment 101 comprises a household having several rooms, spaces, and/or playback zones, including a master bathroom 101 a, a master bedroom 101 b, (referred to herein as “Nick's Room”), a second bedroom 101 c, a family room or den 101 d, an office 101 e, a living room 101 f, a dining room 101 g, a kitchen 101 h, and an outdoor patio 101 i. While certain embodiments and examples are described below in the context of a home environment, the technologies described herein may be implemented in other types of environments. In some embodiments, for example, the MPS 100 can be implemented in one or more commercial settings (e.g., a restaurant, mall, airport, hotel, a retail or other store), one or more vehicles (e.g., a sports utility vehicle, bus, car, a ship, a boat, an airplane), multiple environments (e.g., a combination of home and vehicle environments), and/or another suitable environment where multi-zone audio may be desirable.

Within these rooms and spaces, the MPS 100 includes one or more computing devices. Referring to FIGS. 1A and 1B together, such computing devices can include playback devices 102 (identified individually as playback devices 102 a-102 o), network microphone devices 103 (identified individually as “NMDs” 103 a-102 i), and controller devices 104 a and 104 b (collectively “controller devices 104”). Referring to FIG. 1B, the home environment may include additional and/or other computing devices, including local network devices, such as one or more smart illumination devices 108 (FIG. 1B), a smart thermostat 110, and a local computing device 105 (FIG. 1A). In embodiments described below, one or more of the various playback devices 102 may be configured as portable playback devices, while others may be configured as stationary playback devices. For example, the headphones 102 o (FIG. 1B) are a portable playback device, while the playback device 102 d on the bookcase may be a stationary device. As another example, the playback device 102 c on the Patio may be a battery-powered device, which may allow it to be transported to various areas within the environment 101, and outside of the environment 101, when it is not plugged in to a wall outlet or the like.

With reference still to FIG. 1B, the various playback, network microphone, and controller devices 102, 103, and 104 and/or other network devices of the MPS 100 may be coupled to one another via point-to-point connections and/or over other connections, which may be wired and/or wireless, via a network 111, such as a LAN including a network router 109. For example, the playback device 102 j in the Den 101 d (FIG. 1A), which may be designated as the “Left” device, may have a point-to-point connection with the playback device 102 a, which is also in the Den 101 d and may be designated as the “Right” device. In a related embodiment, the Left playback device 102 j may communicate with other network devices, such as the playback device 102 b, which may be designated as the “Front” device, via a point-to-point connection and/or other connections via the NETWORK 111.

As further shown in FIG. 1B, the MPS 100 may be coupled to one or more remote computing devices 106 via a wide area network (“WAN”) 107. In some embodiments, each remote computing device 106 may take the form of one or more cloud servers. The remote computing devices 106 may be configured to interact with computing devices in the environment 101 in various ways. For example, the remote computing devices 106 may be configured to facilitate streaming and/or controlling playback of media content, such as audio, in the home environment 101.

In some implementations, the various playback devices, NMDs, and/or controller devices 102-104 may be communicatively coupled to at least one remote computing device associated with a VAS and at least one remote computing device associated with a media content service (“MCS”). For instance, in the illustrated example of FIG. 1B, remote computing devices 106 are associated with a VAS 190 and remote computing devices 106 b are associated with an MCS 192. Although only a single VAS 190 and a single MCS 192 are shown in the example of FIG. 1B for purposes of clarity, the MPS 100 may be coupled to multiple, different VASes and/or MCSes. In some implementations, VASes may be operated by one or more of AMAZON, GOOGLE, APPLE, MICROSOFT, SONOS or other voice assistant providers. In some implementations, MCSes may be operated by one or more of SPOTIFY, PANDORA, AMAZON MUSIC, or other media content services.

As further shown in FIG. 1B, the remote computing devices 106 further include remote computing device 106 c configured to perform certain operations, such as remotely facilitating media playback functions, managing device and system status information, directing communications between the devices of the MPS 100 and one or multiple VASes and/or MCSes, among other operations. In one example, the remote computing devices 106 c provide cloud servers for one or more SONOS Wireless HiFi Systems.

In various implementations, one or more of the playback devices 102 may take the form of or include an on-board (e.g., integrated) network microphone device. For example, the playback devices 102 a-e include or are otherwise equipped with corresponding NMDs 103 a-e, respectively. A playback device that includes or is equipped with an NMD may be referred to herein interchangeably as a playback device or an NMD unless indicated otherwise in the description. In some cases, one or more of the NMDs 103 may be a stand-alone device. For example, the NMDs 103 f and 103 g may be stand-alone devices. A stand-alone NMD may omit components and/or functionality that is typically included in a playback device, such as a speaker or related electronics. For instance, in such cases, a stand-alone NMD may not produce audio output or may produce limited audio output (e.g., relatively low-quality audio output).

The various playback and network microphone devices 102 and 103 of the MPS 100 may each be associated with a unique name, which may be assigned to the respective devices by a user, such as during setup of one or more of these devices. For instance, as shown in the illustrated example of FIG. 1B, a user may assign the name “Bookcase” to playback device 102 d because it is physically situated on a bookcase. Similarly, the NMD 103 f may be assigned the named “Island” because it is physically situated on an island countertop in the Kitchen 101 h (FIG. 1A). Some playback devices may be assigned names according to a zone or room, such as the playback devices 102 e, 1021, 102 m, and 102 n, which are named “Bedroom,” “Dining Room,” “Living Room,” and “Office,” respectively. Further, certain playback devices may have functionally descriptive names. For example, the playback devices 102 a and 102 b are assigned the names “Right” and “Front,” respectively, because these two devices are configured to provide specific audio channels during media playback in the zone of the Den 101 d (FIG. 1A). The playback device 102 c in the Patio may be named portable because it is battery-powered and/or readily transportable to different areas of the environment 101. Other naming conventions are possible.

As discussed above, an NMD may detect and process sound from its environment, such as sound that includes background noise mixed with speech spoken by a person in the NMD's vicinity. For example, as sounds are detected by the NMD in the environment, the NMD may process the detected sound to determine if the sound includes speech that contains voice input intended for the NMD and ultimately a particular VAS. For example, the NMD may identify whether speech includes a wake word associated with a particular VAS.

In the illustrated example of FIG. 1B, the NMDs 103 are configured to interact with the VAS 190 over a network via the network 111 and the router 109. Interactions with the VAS 190 may be initiated, for example, when an NMD identifies in the detected sound a potential wake word. The identification causes a wake-word event, which in turn causes the NMD to begin transmitting detected-sound data to the VAS 190. In some implementations, the various local network devices 102-105 (FIG. 1A) and/or remote computing devices 106 c of the MPS 100 may exchange various feedback, information, instructions, and/or related data with the remote computing devices associated with the selected VAS. Such exchanges may be related to or independent of transmitted messages containing voice inputs. In some embodiments, the remote computing device(s) and the MPS 100 may exchange data via communication paths as described herein and/or using a metadata exchange channel as described in U.S. application Ser. No. 15/438,749 filed Feb. 21, 2017, and titled “Voice Control of a Media Playback System,” which is herein incorporated by reference in its entirety.

Upon receiving the stream of sound data, the VAS 190 determines if there is voice input in the streamed data from the NMD, and if so the VAS 190 will also determine an underlying intent in the voice input. The VAS 190 may next transmit a response back to the MPS 100, which can include transmitting the response directly to the NMD that caused the wake-word event. The response is typically based on the intent that the VAS 190 determined was present in the voice input. As an example, in response to the VAS 190 receiving a voice input with an utterance to “Play Hey Jude by The Beatles,” the VAS 190 may determine that the underlying intent of the voice input is to initiate playback and further determine that intent of the voice input is to play the particular song “Hey Jude.” After these determinations, the VAS 190 may transmit a command to a particular MCS 192 to retrieve content (i.e., the song “Hey Jude”), and that MCS 192, in turn, provides (e.g., streams) this content directly to the MPS 100 or indirectly via the VAS 190. In some implementations, the VAS 190 may transmit to the MPS 100 a command that causes the MPS 100 itself to retrieve the content from the MCS 192.

In certain implementations, NMDs may facilitate arbitration amongst one another when voice input is identified in speech detected by two or more NMDs located within proximity of one another. For example, the NMD-equipped playback device 102 d in the environment 101 (FIG. 1A) is in relatively close proximity to the NMD-equipped Living Room playback device 102 m, and both devices 102 d and 102 m may at least sometimes detect the same sound. In such cases, this may require arbitration as to which device is ultimately responsible for providing detected-sound data to the remote VAS. Examples of arbitrating between NMDs may be found, for example, in previously referenced U.S. application Ser. No. 15/438,749.

In certain implementations, an NMD may be assigned to, or otherwise associated with, a designated or default playback device that may not include an NMD. For example, the Island NMD 103 f in the Kitchen 101 h (FIG. 1A) may be assigned to the Dining Room playback device 102 l, which is in relatively close proximity to the Island NMD 103 f. In practice, an NMD may direct an assigned playback device to play audio in response to a remote VAS receiving a voice input from the NMD to play the audio, which the NMD might have sent to the VAS in response to a user speaking a command to play a certain song, album, playlist, etc. Additional details regarding assigning NMDs and playback devices as designated or default devices may be found, for example, in previously referenced U.S. Patent Application No.

Further aspects relating to the different components of the example MPS 100 and how the different components may interact to provide a user with a media experience may be found in the following sections. While discussions herein may generally refer to the example MPS 100, technologies described herein are not limited to applications within, among other things, the home environment described above. For instance, the technologies described herein may be useful in other home environment configurations comprising more or fewer of any of the playback, network microphone, and/or controller devices 102-104. For example, the technologies herein may be utilized within an environment having a single playback device 102 and/or a single NMD 103. In some examples of such cases, the NETWORK 111 (FIG. 1B) may be eliminated and the single playback device 102 and/or the single NMD 103 may communicate directly with the remote computing devices 106-d. In some embodiments, a telecommunication network (e.g., an LTE network, a 5G network, etc.) may communicate with the various playback, network microphone, and/or controller devices 102-104 independent of a LAN.

a. Example Playback & Network Microphone Devices

FIG. 2A is a functional block diagram illustrating certain aspects of one of the playback devices 102 of the MPS 100 of FIGS. 1A and 1B. As shown, the playback device 102 includes various components, each of which is discussed in further detail below, and the various components of the playback device 102 may be operably coupled to one another via a system bus, communication network, or some other connection mechanism. In the illustrated example of FIG. 2A, the playback device 102 may be referred to as an “NMD-equipped” playback device because it includes components that support the functionality of an NMD, such as one of the NMDs 103 shown in FIG. 1A.

As shown, the playback device 102 includes at least one processor 212, which may be a clock-driven computing component configured to process input data according to instructions stored in memory 213. The memory 213 may be a tangible, non-transitory, computer-readable medium configured to store instructions that are executable by the processor 212. For example, the memory 213 may be data storage that can be loaded with software code 214 that is executable by the processor 212 to achieve certain functions.

In one example, these functions may involve the playback device 102 retrieving audio data from an audio source, which may be another playback device. In another example, the functions may involve the playback device 102 sending audio data, detected-sound data (e.g., corresponding to a voice input), and/or other information to another device on a network via at least one network interface 224. In yet another example, the functions may involve the playback device 102 causing one or more other playback devices to synchronously playback audio with the playback device 102. In yet a further example, the functions may involve the playback device 102 facilitating being paired or otherwise bonded with one or more other playback devices to create a multi-channel audio environment. Numerous other example functions are possible, some of which are discussed below.

As just mentioned, certain functions may involve the playback device 102 synchronizing playback of audio content with one or more other playback devices. During synchronous playback, a listener may not perceive time-delay differences between playback of the audio content by the synchronized playback devices. U.S. Pat. No. 8,234,395 filed on Apr. 4, 2004, and titled “System and method for synchronizing operations among a plurality of independently clocked digital data processing devices,” which is hereby incorporated by reference in its entirety, provides in more detail some examples for audio playback synchronization among playback devices.

To facilitate audio playback, the playback device 102 includes audio processing components 216 that are generally configured to process audio prior to the playback device 102 rendering the audio. In this respect, the audio processing components 216 may include one or more digital-to-analog converters (“DAC”), one or more audio preprocessing components, one or more audio enhancement components, one or more digital signal processors (“DSPs”), and so on. In some implementations, one or more of the audio processing components 216 may be a subcomponent of the processor 212. In operation, the audio processing components 216 receive analog and/or digital audio and process and/or otherwise intentionally alter the audio to produce audio signals for playback.

The produced audio signals may then be provided to one or more audio amplifiers 217 for amplification and playback through one or more speakers 218 operably coupled to the amplifiers 217. The audio amplifiers 217 may include components configured to amplify audio signals to a level for driving one or more of the speakers 218.

Each of the speakers 218 may include an individual transducer (e.g., a “driver”) or the speakers 218 may include a complete speaker system involving an enclosure with one or more drivers. A particular driver of a speaker 218 may include, for example, a subwoofer (e.g., for low frequencies), a mid-range driver (e.g., for middle frequencies), and/or a tweeter (e.g., for high frequencies). In some cases, a transducer may be driven by an individual corresponding audio amplifier of the audio amplifiers 217. In some implementations, a playback device may not include the speakers 218, but instead may include a speaker interface for connecting the playback device to external speakers. In certain embodiments, a playback device may include neither the speakers 218 nor the audio amplifiers 217, but instead may include an audio interface (not shown) for connecting the playback device to an external audio amplifier or audio-visual receiver.

In addition to producing audio signals for playback by the playback device 102, the audio processing components 216 may be configured to process audio to be sent to one or more other playback devices, via the network interface 224, for playback. In example scenarios, audio content to be processed and/or played back by the playback device 102 may be received from an external source, such as via an audio line-in interface (e.g., an auto-detecting 3.5 mm audio line-in connection) of the playback device 102 (not shown) or via the network interface 224, as described below.

As shown, the at least one network interface 224, may take the form of one or more wireless interfaces 225 and/or one or more wired interfaces 226. A wireless interface may provide network interface functions for the playback device 102 to wirelessly communicate with other devices (e.g., other playback device(s), NMD(s), and/or controller device(s)) in accordance with a communication protocol (e.g., any wireless standard including IEEE 802.11a, 802.11b, 802.11g, 802.11n, 802.11ac, 802.15, 4G mobile communication standard, and so on). A wired interface may provide network interface functions for the playback device 102 to communicate over a wired connection with other devices in accordance with a communication protocol (e.g., IEEE 802.3). While the network interface 224 shown in FIG. 2A include both wired and wireless interfaces, the playback device 102 may in some implementations include only wireless interface(s) or only wired interface(s).

In general, the network interface 224 facilitates data flow between the playback device 102 and one or more other devices on a data network. For instance, the playback device 102 may be configured to receive audio content over the data network from one or more other playback devices, network devices within a LAN, and/or audio content sources over a WAN, such as the Internet. In one example, the audio content and other signals transmitted and received by the playback device 102 may be transmitted in the form of digital packet data comprising an Internet Protocol (IP)-based source address and IP-based destination addresses. In such a case, the network interface 224 may be configured to parse the digital packet data such that the data destined for the playback device 102 is properly received and processed by the playback device 102.

As shown in FIG. 2A, the playback device 102 also includes voice processing components 220 that are operably coupled to one or more microphones 222. The microphones 222 are configured to detect sound (i.e., acoustic waves) in the environment of the playback device 102, which is then provided to the voice processing components 220. More specifically, each microphone 222 is configured to detect sound and convert the sound into a digital or analog signal representative of the detected sound, which can then cause the voice processing component 220 to perform various functions based on the detected sound, as described in greater detail below. In one implementation, the microphones 222 are arranged as an array of microphones (e.g., an array of six microphones). In some implementations, the playback device 102 includes more than six microphones (e.g., eight microphones or twelve microphones) or fewer than six microphones (e.g., four microphones, two microphones, or a single microphones).

In operation, the voice-processing components 220 are generally configured to detect and process sound received via the microphones 222, identify potential voice input in the detected sound, and extract detected-sound data to enable a VAS, such as the VAS 190 (FIG. 1B), to process voice input identified in the detected-sound data. The voice processing components 220 may include one or more analog-to-digital converters, an acoustic echo canceller (“AEC”), a spatial processor (e.g., one or more multi-channel Wiener filters, one or more other filters, and/or one or more beam former components), one or more buffers (e.g., one or more circular buffers), one or more wake-word engines, one or more voice extractors, and/or one or more speech processing components (e.g., components configured to recognize a voice of a particular user or a particular set of users associated with a household), among other example voice processing components. In example implementations, the voice processing components 220 may include or otherwise take the form of one or more DSPs or one or more modules of a DSP. In this respect, certain voice processing components 220 may be configured with particular parameters (e.g., gain and/or spectral parameters) that may be modified or otherwise tuned to achieve particular functions. In some implementations, one or more of the voice processing components 220 may be a subcomponent of the processor 212.

As further shown in FIG. 2A, the playback device 102 also includes power components 227. The power components 227 include at least an external power source interface 228, which may be coupled to a power source (not shown) via a power cable or the like that physically connects the playback device 102 to an electrical outlet or some other external power source. Other power components may include, for example, transformers, converters, and like components configured to format electrical power.

In some implementations, the power components 227 of the playback device 102 may additionally include an internal power source 229 (e.g., one or more batteries) configured to power the playback device 102 without a physical connection to an external power source. When equipped with the internal power source 229, the playback device 102 may operate independent of an external power source. In some such implementations, the external power source interface 228 may be configured to facilitate charging the internal power source 229. As discussed before, a playback device comprising an internal power source may be referred to herein as a “portable playback device.” On the other hand, a playback device that operates using an external power source may be referred to herein as a “stationary playback device,” although such a device may in fact be moved around a home or other environment.

The playback device 102 further includes a user interface 240 that may facilitate user interactions independent of or in conjunction with user interactions facilitated by one or more of the controller devices 104. In various embodiments, the user interface 240 includes one or more physical buttons and/or supports graphical interfaces provided on touch sensitive screen(s) and/or surface(s), among other possibilities, for a user to directly provide input. The user interface 240 may further include one or more of lights (e.g., LEDs) and the speakers to provide visual and/or audio feedback to a user.

As an illustrative example, FIG. 2B shows an example housing 230 of the playback device 102 that includes a user interface in the form of a control area 232 at a top portion 234 of the housing 230. The control area 232 includes buttons 236 a-c for controlling audio playback, volume level, and other functions. The control area 232 also includes a button 236 d for toggling the microphones 222 to either an on state or an off state.

As further shown in FIG. 2B, the control area 232 is at least partially surrounded by apertures formed in the top portion 234 of the housing 230 through which the microphones 222 (not visible in FIG. 2B) receive the sound in the environment of the playback device 102. The microphones 222 may be arranged in various positions along and/or within the top portion 234 or other areas of the housing 230 so as to detect sound from one or more directions relative to the playback device 102.

By way of illustration, SONOS, Inc. presently offers (or has offered) for sale certain playback devices that may implement certain of the embodiments disclosed herein, including a “PLAY:1,” “PLAY:3,” “PLAY:5,” “PLAYBAR,” “CONNECT:AMP,” “PLAYBASE,” “BEAM,” “CONNECT,” and “SUB.” Any other past, present, and/or future playback devices may additionally or alternatively be used to implement the playback devices of example embodiments disclosed herein. Additionally, it should be understood that a playback device is not limited to the examples illustrated in FIG. 2A or 2B or to the SONOS product offerings. For example, a playback device may include, or otherwise take the form of, a wired or wireless headphone set, which may operate as a part of the MPS 100 via a network interface or the like. In another example, a playback device may include or interact with a docking station for personal mobile media playback devices. In yet another example, a playback device may be integral to another device or component such as a television, a lighting fixture, or some other device for indoor or outdoor use.

FIG. 2C is a diagram of an example voice input 280 that may be processed by an NMD or an NMD-equipped playback device. The voice input 280 may include a keyword portion 280 a and an utterance portion 280 b. The keyword portion 280 a may include a wake word or a local keyword.

In the case of a wake word, the keyword portion 280 a corresponds to detected sound that caused a VAS wake-word event. In practice, a wake word is typically a predetermined nonce word or phrase used to “wake up” an NMD and cause it to invoke a particular voice assistant service (“VAS”) to interpret the intent of voice input in detected sound. For example, a user might speak the wake word “Alexa” to invoke the AMAZON® VAS, “Ok, Google” to invoke the GOOGLE® VAS, or “Hey, Siri” to invoke the APPLE® VAS, among other examples. In practice, a wake word may also be referred to as, for example, an activation-, trigger-, wakeup-word or -phrase, and may take the form of any suitable word, combination of words (e.g., a particular phrase), and/or some other audio cue.

The utterance portion 280 b corresponds to detected sound that potentially comprises a user request following the keyword portion 280 a. An utterance portion 280 b can be processed to identify the presence of any words in detected-sound data by the NMD in response to the event caused by the keyword portion 280 a. In various implementations, an underlying intent can be determined based on the words in the utterance portion 280 b. In certain implementations, an underlying intent can also be based or at least partially based on certain words in the keyword portion 280 a, such as when keyword portion includes a command keyword. In any case, the words may correspond to one or more commands, as well as a certain command and certain keywords.

A keyword in the voice utterance portion 280 b may be, for example, a word identifying a particular device or group in the MPS 100. For instance, in the illustrated example, the keywords in the voice utterance portion 280 b may be one or more words identifying one or more zones in which the music is to be played, such as the Living Room and the Dining Room (FIG. 1A). In some cases, the utterance portion 280 b may include additional information, such as detected pauses (e.g., periods of non-speech) between words spoken by a user, as shown in FIG. 2C. The pauses may demarcate the locations of separate commands, keywords, or other information spoke by the user within the utterance portion 280 b.

Based on certain command criteria, the NMD and/or a remote VAS may take actions as a result of identifying one or more commands in the voice input. Command criteria may be based on the inclusion of certain keywords within the voice input, among other possibilities. Additionally, AMAstate and/or zone-state variables in conjunction with identification of one or more particular commands. Control-state variables may include, for example, indicators identifying a level of volume, a queue associated with one or more devices, and playback state, such as whether devices are playing a queue, paused, etc. Zone-state variables may include, for example, indicators identifying which, if any, zone players are grouped.

In some implementations, the MPS 100 is configured to temporarily reduce the volume of audio content that it is playing upon detecting a certain keyword, such as a wake word, in the keyword portion 280 a. The MPS 100 may restore the volume after processing the voice input 280. Such a process can be referred to as ducking, examples of which are disclosed in U.S. patent application Ser. No. 15/438,749, incorporated by reference herein in its entirety.

FIG. 2D shows an example sound specimen. In this example, the sound specimen corresponds to the sound-data stream (e.g., one or more audio frames) associated with a spotted wake word or command keyword in the keyword portion 280 a of FIG. 2A. As illustrated, the example sound specimen comprises sound detected in an NMD's environment (i) immediately before a wake or command word was spoken, which may be referred to as a pre-roll portion (between times t₀ and t₁), (ii) while a wake or command word was spoken, which may be referred to as a wake-meter portion (between times t₁ and t₂), and/or (iii) after the wake or command word was spoken, which may be referred to as a post-roll portion (between times t₂ and t₃). Other sound specimens are also possible. In various implementations, aspects of the sound specimen can be evaluated according to an acoustic model which aims to map mels/spectral features to phonemes in a given language model for further processing. For example, automatic speech recognition (ASR) may include such mapping for command-keyword detection. Wake-word detection engines, by contrast, may be precisely tuned to identify a specific wake-word, and a downstream action of invoking a VAS (e.g., by targeting only nonce words in the voice input processed by the playback device).

ASR for local keyword detection may be tuned to accommodate a wide range of keywords (e.g., 5, 10, 100, 1,000, 10,000 keywords). Local keyword detection, in contrast to wake-word detection, may involve feeding ASR output to an onboard, local NLU which together with the ASR determine when local keyword events have occurred. In some implementations described below, the local NLU may determine an intent based on one or more keywords in the ASR output produced by a particular voice input. In these or other implementations, a playback device may act on a detected command keyword event only when the playback devices determines that certain conditions have been met, such as environmental conditions (e.g., low background noise).

b. Example Playback Device Configurations

FIGS. 3A-3E show example configurations of playback devices. Referring first to FIG. 3A, in some example instances, a single playback device may belong to a zone. For example, the playback device 102 c (FIG. 1A) on the Patio may belong to Zone A. In some implementations described below, multiple playback devices may be “bonded” to form a “bonded pair,” which together form a single zone. For example, the playback device 102 f (FIG. 1A) named “Bed 1” in FIG. 3A may be bonded to the playback device 102 g (FIG. 1A) named “Bed 2” in FIG. 3A to form Zone B. Bonded playback devices may have different playback responsibilities (e.g., channel responsibilities). In another implementation described below, multiple playback devices may be merged to form a single zone. For example, the playback device 102 d named “Bookcase” may be merged with the playback device 102 m named “Living Room” to form a single Zone C. The merged playback devices 102 d and 102 m may not be specifically assigned different playback responsibilities. That is, the merged playback devices 102 d and 102 m may, aside from playing audio content in synchrony, each play audio content as they would if they were not merged.

For purposes of control, each zone in the MPS 100 may be represented as a single user interface (“UI”) entity. For example, as displayed by the controller devices 104, Zone A may be provided as a single entity named “Portable,” Zone B may be provided as a single entity named “Stereo,” and Zone C may be provided as a single entity named “Living Room.”

In various embodiments, a zone may take on the name of one of the playback devices belonging to the zone. For example, Zone C may take on the name of the Living Room device 102 m (as shown). In another example, Zone C may instead take on the name of the Bookcase device 102 d. In a further example, Zone C may take on a name that is some combination of the Bookcase device 102 d and Living Room device 102 m. The name that is chosen may be selected by a user via inputs at a controller device 104. In some embodiments, a zone may be given a name that is different than the device(s) belonging to the zone. For example, Zone B in FIG. 3A is named “Stereo” but none of the devices in Zone B have this name. In one aspect, Zone B is a single UI entity representing a single device named “Stereo,” composed of constituent devices “Bed 1” and “Bed 2.” In one implementation, the Bed 1 device may be playback device 102 f in the master bedroom 101 h (FIG. 1A) and the Bed 2 device may be the playback device 102 g also in the master bedroom 101 h (FIG. 1A).

As noted above, playback devices that are bonded may have different playback responsibilities, such as playback responsibilities for certain audio channels. For example, as shown in FIG. 3B, the Bed 1 and Bed 2 devices 102 f and 102 g may be bonded so as to produce or enhance a stereo effect of audio content. In this example, the Bed 1 playback device 102 f may be configured to play a left channel audio component, while the Bed 2 playback device 102 g may be configured to play a right channel audio component. In some implementations, such stereo bonding may be referred to as “pairing.”

Additionally, playback devices that are configured to be bonded may have additional and/or different respective speaker drivers. As shown in FIG. 3C, the playback device 102 b named “Front” may be bonded with the playback device 102 k named “SUB.” The Front device 102 b may render a range of mid to high frequencies, and the SUB device 102 k may render low frequencies as, for example, a subwoofer. When unbonded, the Front device 102 b may be configured to render a full range of frequencies. As another example, FIG. 3D shows the Front and SUB devices 102 b and 102 k further bonded with Right and Left playback devices 102 a and 102 j, respectively. In some implementations, the Right and Left devices 102 a and 102 j may form surround or “satellite” channels of a home theater system. The bonded playback devices 102 a, 102 b, 102 j, and 102 k may form a single Zone D (FIG. 3A).

In some implementations, playback devices may also be “merged.” In contrast to certain bonded playback devices, playback devices that are merged may not have assigned playback responsibilities, but may each render the full range of audio content that each respective playback device is capable of. Nevertheless, merged devices may be represented as a single UI entity (i.e., a zone, as discussed above). For instance, FIG. 3E shows the playback devices 102 d and 102 m in the Living Room merged, which would result in these devices being represented by the single UI entity of Zone C. In one embodiment, the playback devices 102 d and 102 m may playback audio in synchrony, during which each outputs the full range of audio content that each respective playback device 102 d and 102 m is capable of rendering.

In some embodiments, a stand-alone NMD may be in a zone by itself. For example, the NMD 103 h from FIG. 1A is named “Closet” and forms Zone I in FIG. 3A. An NMD may also be bonded or merged with another device so as to form a zone. For example, the NMD device 103 f named “Island” may be bonded with the playback device 102 i Kitchen, which together form Zone F, which is also named “Kitchen.” Additional details regarding assigning NMDs and playback devices as designated or default devices may be found, for example, in previously referenced U.S. patent application Ser. No. 15/438,749. In some embodiments, a stand-alone NMD may not be assigned to a zone.

Zones of individual, bonded, and/or merged devices may be arranged to form a set of playback devices that playback audio in synchrony. Such a set of playback devices may be referred to as a “group,” “zone group,” “synchrony group,” or “playback group.” In response to inputs provided via a controller device 104, playback devices may be dynamically grouped and ungrouped to form new or different groups that synchronously play back audio content. For example, referring to FIG. 3A, Zone A may be grouped with Zone B to form a zone group that includes the playback devices of the two zones. As another example, Zone A may be grouped with one or more other Zones C-I. The Zones A-I may be grouped and ungrouped in numerous ways. For example, three, four, five, or more (e.g., all) of the Zones A-I may be grouped. When grouped, the zones of individual and/or bonded playback devices may play back audio in synchrony with one another, as described in previously referenced U.S. Pat. No. 8,234,395. Grouped and bonded devices are example types of associations between portable and stationary playback devices that may be caused in response to a trigger event, as discussed above and described in greater detail below.

In various implementations, the zones in an environment may be assigned a particular name, which may be the default name of a zone within a zone group or a combination of the names of the zones within a zone group, such as “Dining Room+Kitchen,” as shown in FIG. 3A. In some embodiments, a zone group may be given a unique name selected by a user, such as “Nick's Room,” as also shown in FIG. 3A. The name “Nick's Room” may be a name chosen by a user over a prior name for the zone group, such as the room name “Master Bedroom.”

Referring back to FIG. 2A, certain data may be stored in the memory 213 as one or more state variables that are periodically updated and used to describe the state of a playback zone, the playback device(s), and/or a zone group associated therewith. The memory 213 may also include the data associated with the state of the other devices of the MPS 100, which may be shared from time to time among the devices so that one or more of the devices have the most recent data associated with the system.

In some embodiments, the memory 213 of the playback device 102 may store instances of various variable types associated with the states. Variables instances may be stored with identifiers (e.g., tags) corresponding to type. For example, certain identifiers may be a first type “al” to identify playback device(s) of a zone, a second type “μl” to identify playback device(s) that may be bonded in the zone, and a third type “c 1” to identify a zone group to which the zone may belong. As a related example, in FIG. 1A, identifiers associated with the Patio may indicate that the Patio is the only playback device of a particular zone and not in a zone group. Identifiers associated with the Living Room may indicate that the Living Room is not grouped with other zones but includes bonded playback devices 102 a, 102 b, 102 j, and 102 k. Identifiers associated with the Dining Room may indicate that the Dining Room is part of Dining Room+Kitchen group and that devices 103 f and 102 i are bonded. Identifiers associated with the Kitchen may indicate the same or similar information by virtue of the Kitchen being part of the Dining Room+Kitchen zone group. Other example zone variables and identifiers are described below.

In yet another example, the MPS 100 may include variables or identifiers representing other associations of zones and zone groups, such as identifiers associated with Areas, as shown in FIG. 3A. An Area may involve a cluster of zone groups and/or zones not within a zone group. For instance, FIG. 3A shows a first area named “First Area” and a second area named “Second Area.” The First Area includes zones and zone groups of the Patio, Den, Dining Room, Kitchen, and Bathroom. The Second Area includes zones and zone groups of the Bathroom, Nick's Room, Bedroom, and Living Room. In one aspect, an Area may be used to invoke a cluster of zone groups and/or zones that share one or more zones and/or zone groups of another cluster. In this respect, such an Area differs from a zone group, which does not share a zone with another zone group. Further examples of techniques for implementing Areas may be found, for example, in U.S. application Ser. No. 15/682,506 filed Aug. 21, 2017 and titled “Room Association Based on Name,” and U.S. Pat. No. 8,483,853 filed Sep. 11, 2007, and titled “Controlling and manipulating groupings in a multi-zone media system.” Each of these applications is incorporated herein by reference in its entirety. In some embodiments, the MPS 100 may not implement Areas, in which case the system may not store variables associated with Areas.

The memory 213 may be further configured to store other data. Such data may pertain to audio sources accessible by the playback device 102 or a playback queue that the playback device (or some other playback device(s)) may be associated with. In embodiments described below, the memory 213 is configured to store a set of command data for selecting a particular VAS when processing voice inputs. During operation, one or more playback zones in the environment of FIG. 1A may each be playing different audio content. For instance, the user may be grilling in the Patio zone and listening to hip hop music being played by the playback device 102 c, while another user may be preparing food in the Kitchen zone and listening to classical music being played by the playback device 102 i. In another example, a playback zone may play the same audio content in synchrony with another playback zone.

For instance, the user may be in the Office zone where the playback device 102 n is playing the same hip-hop music that is being playing by playback device 102 c in the Patio zone. In such a case, playback devices 102 c and 102 n may be playing the hip-hop in synchrony such that the user may seamlessly (or at least substantially seamlessly) enjoy the audio content that is being played out-loud while moving between different playback zones. Synchronization among playback zones may be achieved in a manner similar to that of synchronization among playback devices, as described in previously referenced U.S. Pat. No. 8,234,395.

As suggested above, the zone configurations of the MPS 100 may be dynamically modified. As such, the MPS 100 may support numerous configurations. For example, if a user physically moves one or more playback devices to or from a zone, the MPS 100 may be reconfigured to accommodate the change(s). For instance, if the user physically moves the playback device 102 c from the Patio zone to the Office zone, the Office zone may now include both the playback devices 102 c and 102 n. In some cases, the user may pair or group the moved playback device 102 c with the Office zone and/or rename the players in the Office zone using, for example, one of the controller devices 104 and/or voice input. As another example, if one or more playback devices 102 are moved to a particular space in the home environment that is not already a playback zone, the moved playback device(s) may be renamed or associated with a playback zone for the particular space.

Further, different playback zones of the MPS 100 may be dynamically combined into zone groups or split up into individual playback zones. For example, the Dining Room zone and the Kitchen zone may be combined into a zone group for a dinner party such that playback devices 102 i and 102 l may render audio content in synchrony. As another example, bonded playback devices in the Den zone may be split into (i) a television zone and (ii) a separate listening zone. The television zone may include the Front playback device 102 b. The listening zone may include the Right, Left, and SUB playback devices 102 a, 102 j, and 102 k, which may be grouped, paired, or merged, as described above. Splitting the Den zone in such a manner may allow one user to listen to music in the listening zone in one area of the living room space, and another user to watch the television in another area of the living room space. In a related example, a user may utilize either of the NMD 103 a or 103 b (FIG. 1B) to control the Den zone before it is separated into the television zone and the listening zone. Once separated, the listening zone may be controlled, for example, by a user in the vicinity of the NMD 103 a, and the television zone may be controlled, for example, by a user in the vicinity of the NMD 103 b. As described above, however, any of the NMDs 103 may be configured to control the various playback and other devices of the MPS 100.

c. Example Controller Devices

FIG. 4 is a functional block diagram illustrating certain aspects of a selected one of the controller devices 104 of the MPS 100 of FIG. 1A. Such controller devices may also be referred to herein as a “control device” or “controller.” The controller device shown in FIG. 4 may include components that are generally similar to certain components of the network devices described above, such as a processor 412, memory 413 storing program software 414, at least one network interface 424, and one or more microphones 422. In one example, a controller device may be a dedicated controller for the MPS 100. In another example, a controller device may be a network device on which media playback system controller application software may be installed, such as for example, an iPhone™, iPad™ or any other smart phone, tablet, or network device (e.g., a networked computer such as a PC or Mac™).

The memory 413 of the controller device 104 may be configured to store controller application software and other data associated with the MPS 100 and/or a user of the system 100. The memory 413 may be loaded with instructions in software 414 that are executable by the processor 412 to achieve certain functions, such as facilitating user access, control, and/or configuration of the MPS 100. The controller device 104 is configured to communicate with other network devices via the network interface 424, which may take the form of a wireless interface, as described above.

In one example, system information (e.g., such as a state variable) may be communicated between the controller device 104 and other devices via the network interface 424. For instance, the controller device 104 may receive playback zone and zone group configurations in the MPS 100 from a playback device, an NMD, or another network device. Likewise, the controller device 104 may transmit such system information to a playback device or another network device via the network interface 424. In some cases, the other network device may be another controller device.

The controller device 104 may also communicate playback device control commands, such as volume control and audio playback control, to a playback device via the network interface 424. As suggested above, changes to configurations of the MPS 100 may also be performed by a user using the controller device 104. The configuration changes may include adding/removing one or more playback devices to/from a zone, adding/removing one or more zones to/from a zone group, forming a bonded or merged player, separating one or more playback devices from a bonded or merged player, among others.

As shown in FIG. 4, the controller device 104 also includes a user interface 440 that is generally configured to facilitate user access and control of the MPS 100. The user interface 440 may include a touch-screen display or other physical interface configured to provide various graphical controller interfaces, such as the controller interfaces 540 a and 540 b shown in FIGS. 5A and 5B. Referring to FIGS. 5A and 5B together, the controller interfaces 540 a and 540 b includes a playback control region 542, a playback zone region 543, a playback status region 544, a playback queue region 546, and a sources region 548. The user interface as shown is just one example of an interface that may be provided on a network device, such as the controller device shown in FIG. 4, and accessed by users to control a media playback system, such as the MPS 100. Other user interfaces of varying formats, styles, and interactive sequences may alternatively be implemented on one or more network devices to provide comparable control access to a media playback system.

The playback control region 542 (FIG. 5A) may include selectable icons (e.g., by way of touch or by using a cursor) that, when selected, cause playback devices in a selected playback zone or zone group to play or pause, fast forward, rewind, skip to next, skip to previous, enter/exit shuffle mode, enter/exit repeat mode, enter/exit cross fade mode, etc. The playback control region 542 may also include selectable icons that, when selected, modify equalization settings and/or playback volume, among other possibilities.

The playback zone region 543 (FIG. 5B) may include representations of playback zones within the MPS 100. The playback zones regions 543 may also include a representation of zone groups, such as the Dining Room+Kitchen zone group, as shown.

In some embodiments, the graphical representations of playback zones may be selectable to bring up additional selectable icons to manage or configure the playback zones in the MPS 100, such as a creation of bonded zones, creation of zone groups, separation of zone groups, and renaming of zone groups, among other possibilities.

For example, as shown, a “group” icon may be provided within each of the graphical representations of playback zones. The “group” icon provided within a graphical representation of a particular zone may be selectable to bring up options to select one or more other zones in the MPS 100 to be grouped with the particular zone. Once grouped, playback devices in the zones that have been grouped with the particular zone will be configured to play audio content in synchrony with the playback device(s) in the particular zone. Analogously, a “group” icon may be provided within a graphical representation of a zone group. In this case, the “group” icon may be selectable to bring up options to deselect one or more zones in the zone group to be removed from the zone group. Other interactions and implementations for grouping and ungrouping zones via a user interface are also possible. The representations of playback zones in the playback zone region 543 (FIG. 5B) may be dynamically updated as playback zone or zone group configurations are modified.

The playback status region 544 (FIG. 5A) may include graphical representations of audio content that is presently being played, previously played, or scheduled to play next in the selected playback zone or zone group. The selected playback zone or zone group may be visually distinguished on a controller interface, such as within the playback zone region 543 and/or the playback status region 544. The graphical representations may include track title, artist name, album name, album year, track length, and/or other relevant information that may be useful for the user to know when controlling the MPS 100 via a controller interface.

The playback queue region 546 may include graphical representations of audio content in a playback queue associated with the selected playback zone or zone group. In some embodiments, each playback zone or zone group may be associated with a playback queue comprising information corresponding to zero or more audio items for playback by the playback zone or zone group. For instance, each audio item in the playback queue may comprise a uniform resource identifier (URI), a uniform resource locator (URL), or some other identifier that may be used by a playback device in the playback zone or zone group to find and/or retrieve the audio item from a local audio content source or a networked audio content source, which may then be played back by the playback device.

In one example, a playlist may be added to a playback queue, in which case information corresponding to each audio item in the playlist may be added to the playback queue. In another example, audio items in a playback queue may be saved as a playlist. In a further example, a playback queue may be empty, or populated but “not in use” when the playback zone or zone group is playing continuously streamed audio content, such as Internet radio that may continue to play until otherwise stopped, rather than discrete audio items that have playback durations. In an alternative embodiment, a playback queue can include Internet radio and/or other streaming audio content items and be “in use” when the playback zone or zone group is playing those items. Other examples are also possible.

When playback zones or zone groups are “grouped” or “ungrouped,” playback queues associated with the affected playback zones or zone groups may be cleared or re-associated. For example, if a first playback zone including a first playback queue is grouped with a second playback zone including a second playback queue, the established zone group may have an associated playback queue that is initially empty, that contains audio items from the first playback queue (such as if the second playback zone was added to the first playback zone), that contains audio items from the second playback queue (such as if the first playback zone was added to the second playback zone), or a combination of audio items from both the first and second playback queues. Subsequently, if the established zone group is ungrouped, the resulting first playback zone may be re-associated with the previous first playback queue or may be associated with a new playback queue that is empty or contains audio items from the playback queue associated with the established zone group before the established zone group was ungrouped. Similarly, the resulting second playback zone may be re-associated with the previous second playback queue or may be associated with a new playback queue that is empty or contains audio items from the playback queue associated with the established zone group before the established zone group was ungrouped. Other examples are also possible.

With reference still to FIGS. 5A and 5B, the graphical representations of audio content in the playback queue region 646 (FIG. 5A) may include track titles, artist names, track lengths, and/or other relevant information associated with the audio content in the playback queue. In one example, graphical representations of audio content may be selectable to bring up additional selectable icons to manage and/or manipulate the playback queue and/or audio content represented in the playback queue. For instance, a represented audio content may be removed from the playback queue, moved to a different position within the playback queue, or selected to be played immediately, or after any currently playing audio content, among other possibilities. A playback queue associated with a playback zone or zone group may be stored in a memory on one or more playback devices in the playback zone or zone group, on a playback device that is not in the playback zone or zone group, and/or some other designated device. Playback of such a playback queue may involve one or more playback devices playing back media items of the queue, perhaps in sequential or random order.

The sources region 548 may include graphical representations of selectable audio content sources and/or selectable voice assistants associated with a corresponding VAS. The VASes may be selectively assigned. In some examples, multiple VASes, such as AMAZON's Alexa, MICROSOFT's Cortana, etc., may be invokable by the same NMD. In some embodiments, a user may assign a VAS exclusively to one or more NMDs. For example, a user may assign a first VAS to one or both of the NMDs 102 a and 102 b in the Living Room shown in FIG. 1A, and a second VAS to the NMD 103 f in the Kitchen. Other examples are possible.

d. Example Audio Content Sources

The audio sources in the sources region 548 may be audio content sources from which audio content may be retrieved and played by the selected playback zone or zone group. One or more playback devices in a zone or zone group may be configured to retrieve for playback audio content (e.g., according to a corresponding URI or URL for the audio content) from a variety of available audio content sources. In one example, audio content may be retrieved by a playback device directly from a corresponding audio content source (e.g., via a line-in connection). In another example, audio content may be provided to a playback device over a network via one or more other playback devices or network devices. As described in greater detail below, in some embodiments audio content may be provided by one or more media content services.

Example audio content sources may include a memory of one or more playback devices in a media playback system such as the MPS 100 of FIG. 1, local music libraries on one or more network devices (e.g., a controller device, a network-enabled personal computer, or a networked-attached storage (“NAS”)), streaming audio services providing audio content via the Internet (e.g., cloud-based music services), or audio sources connected to the media playback system via a line-in input connection on a playback device or network device, among other possibilities.

In some embodiments, audio content sources may be added or removed from a media playback system such as the MPS 100 of FIG. 1A. In one example, an indexing of audio items may be performed whenever one or more audio content sources are added, removed, or updated. Indexing of audio items may involve scanning for identifiable audio items in all folders/directories shared over a network accessible by playback devices in the media playback system and generating or updating an audio content database comprising metadata (e.g., title, artist, album, track length, among others) and other associated information, such as a URI or URL for each identifiable audio item found. Other examples for managing and maintaining audio content sources may also be possible.

FIG. 6 is a message flow diagram illustrating data exchanges between devices of the MPS 100. At step 650 a, the MPS 100 receives an indication of selected media content (e.g., one or more songs, albums, playlists, podcasts, videos, stations) via the control device 104. The selected media content can comprise, for example, media items stored locally on or more devices (e.g., the audio source 105 of FIG. 1C) connected to the media playback system and/or media items stored on one or more media service servers (one or more of the remote computing devices 106 of FIG. 1B). In response to receiving the indication of the selected media content, the control device 104 transmits a message 651 a to the playback device 102 (FIGS. 1A-1C) to add the selected media content to a playback queue on the playback device 102.

At step 650 b, the playback device 102 receives the message 651 a and adds the selected media content to the playback queue for play back.

At step 650 c, the control device 104 receives input corresponding to a command to play back the selected media content. In response to receiving the input corresponding to the command to play back the selected media content, the control device 104 transmits a message 651 b to the playback device 102 causing the playback device 102 to play back the selected media content. In response to receiving the message 651 b, the playback device 102 transmits a message 651 c to the computing device 106 requesting the selected media content. The computing device 106, in response to receiving the message 651 c, transmits a message 651 d comprising data (e.g., audio data, video data, a URL, a URI) corresponding to the requested media content.

At step 650 d, the playback device 102 receives the message 651 d with the data corresponding to the requested media content and plays back the associated media content.

At step 650 e, the playback device 102 optionally causes one or more other devices to play back the selected media content. In one example, the playback device 102 is one of a bonded zone of two or more players (FIG. 1M). The playback device 102 can receive the selected media content and transmit all or a portion of the media content to other devices in the bonded zone. In another example, the playback device 102 is a coordinator of a group and is configured to transmit and receive timing information from one or more other devices in the group. The other one or more devices in the group can receive the selected media content from the computing device 106, and begin playback of the selected media content in response to a message from the playback device 102 such that all of the devices in the group play back the selected media content in synchrony.

III. Example Network Microphone Device

FIG. 7A is a functional block diagram illustrating certain aspects of an example network microphone device (NMD) 703. Generally, the NMD 703 may be similar to the network microphone device(s) 103 illustrated in FIGS. 1A and 1B. As shown, the NMD 703 includes various components, each of which is discussed in further detail below. The various components of the NMD 703 may be operably coupled to one another via a system bus, communication network, or some other connection mechanism.

Many of these components are similar to the playback device 102 of FIG. 2A. In some examples, the NMD 703 may be implemented in a playback device 102. In such cases, the NMD 703 might not include duplicate components (e.g., a network interface 224 and a network 724), but may instead share several components to carry out both playback and voice control functions. Alternatively, within some examples, the NMD 703 is not designed for audio content playback and therefore may exclude audio processing components 216, amplifiers 217, and/or speakers 218 or may include relatively less capable versions of these components (e.g., less powerful amplifier(s) 217 and/or smaller speakers 218)).

As shown, the NMD 703 includes at least one processor 712, which may be a clock-driven computing component configured to process input data according to instructions stored in memory 713. The memory 713 may be a tangible, non-transitory, computer-readable medium configured to store instructions that are executable by the processor 712. For example, the memory 713 may be data storage that can be loaded with software code 714 that is executable by the processor 712 to achieve certain functions.

The at least one network interface 724 may take the form of one or more wireless interfaces 725 and/or one or more wired interfaces 726. The wireless interface 725 may provide network interface functions for the NMD 703 to wirelessly communicate with other devices (e.g., playback device(s) 102, other NMD(s) 103, and/or controller device(s) 104) in accordance with a communication protocol (e.g., any wireless standard including IEEE 802.11a, 802.11b, 802.11g, 802.11n, 802.11ac, 802.15, 4G mobile communication standard, and so on). The wired interface 726 may provide network interface functions for the NMD 703 to communicate over a wired connection with other devices in accordance with a communication protocol (e.g., IEEE 802.3). While the network interface 724 shown in FIG. 7A includes both wired and wireless interfaces, the playback device 102 may in various implementations include only wireless interface(s) or only wired interface(s).

As shown in FIG. 7A, the NMD 703 also includes voice processing components 720 that are operably coupled to microphones 722. The microphones 722 are configured to detect sound (i.e., acoustic waves) in the environment of the NMD 703, which is then provided to the voice processing components 720. More specifically, the microphones 722 are configured to detect sound and convert the sound into a digital or analog signal representative of the detected sound, which can then cause the voice processing component 720 to perform various functions based on the detected sound, as described in greater detail below. In one implementation, the microphones 722 are arranged as one or more arrays of microphones (e.g., an array of six microphones). In some implementations, the NMD 703 includes more than six microphones (e.g., eight microphones or twelve microphones) or fewer than six microphones (e.g., four microphones, two microphones, or a single microphone).

In operation, similar to the voice-processing components 220 of the NMD-equipped playback device 102 the voice-processing components 720 are generally configured to detect and process sound received via the microphones 722, identify potential voice input in the detected sound, and extract detected-sound data to enable processing of the voice input by a cloud-based VAS, such as the VAS 190 (FIG. 1B), or a local NLU. The voice processing components 720 may include one or more analog-to-digital converters, an acoustic echo canceller (“AEC”), a spatial processor, one or more buffers (e.g., one or more circular buffers), one or more wake-word engines, one or more voice extractors, and/or one or more speech processing components (e.g., components configured to recognize a voice of a particular user or a particular set of users associated with a household), among other example voice processing components. In example implementations, the voice processing components 720 may include or otherwise take the form of one or more DSPs or one or more modules of a DSP. In some implementations, one or more of the voice processing components 720 may be a subcomponent of the processor 712.

As further shown in FIG. 7A, the NMD 703 also includes power components 727. The power components 727 include at least an external power source interface 728, which may be coupled to a power source (not shown) via a power cable or the like that physically connects the NMD 703 to an electrical outlet or some other external power source. Other power components may include, for example, transformers, converters, and like components configured to format electrical power.

In some implementations, the power components 727 of the NMD 703 may additionally include an internal power source 729 (e.g., one or more batteries) configured to power the NMD 703 without a physical connection to an external power source. When equipped with the internal power source 729, the NMD 703 may operate independent of an external power source. In some such implementations, the external power source interface 728 may be configured to facilitate charging the internal power source 729. As discussed before, a NMD comprising an internal power source may be referred to herein as a “portable NMD.” On the other hand, a NMD that operates using an external power source may be referred to herein as a “stationary NMD,” although such a device may in fact be moved around a home or other environment (e.g., to be connected to different power outlets of a home or other building).

The NMD 703 further includes a user interface 740 that may facilitate user interactions independent of or in conjunction with user interactions facilitated by one or more of the controller devices 104. In various embodiments, the user interface 740 includes one or more physical buttons and/or supports graphical interfaces provided on touch sensitive screen(s) and/or surface(s), among other possibilities, for a user to directly provide input. The user interface 740 may further include one or more of lights (e.g., LEDs) and the speakers to provide visual and/or audio feedback to a user.

As an illustrative example, FIG. 7B shows an isometric view of the NMD 703. As shown in FIG. 7B, the NMD 703 includes a housing 730. The housing 730 may carry one or more components shown in FIG. 7A. The housing 730 includes a user interface 740 a carried on the top portion 734 of the housing 730. The user interface 740 includes buttons 736 a-736 c for controlling audio playback, volume level, and other functions. The user interface 740 a also includes a button 736 d for toggling the microphones 722 to either an on state or an off state.

As further shown in FIG. 7B, apertures are formed in the top portion 734 of the housing 730 through which the microphones 722 receive sound in the environment of the NMD 703. The microphones 722 may be arranged in various positions along and/or within the top portion 734 or other areas of the housing 730 so as to detect sound from one or more directions relative to the NMD 703.

FIG. 7C is a functional block diagram showing aspects of an NMD 703 configured in accordance with embodiments of the disclosure. As described in more detail below, the NMD 703 is configured to handle certain voice inputs locally, without necessarily transmitting data representing the voice input to a VAS. The NMD 703 is also configured to process other voice inputs using a voice assistant service.

Referring to the FIG. 7C, the NMD 703 includes voice capture components (“VCC”) 760, a VAS wake-word engine 770 a, and a voice extractor 773. The VAS wake-word engine 770 a and the voice extractor 773 are operably coupled to the VCC 760. The NMD 703 a further a local wake-word engine 771 operably coupled to the VCC 760.

The NMD 703 further includes microphones 722. The microphones 722 of the NMD 703 are configured to provide detected sound, S_(D), from the environment of the NMD 703 to the VCC 760. The detected sound S_(D) may take the form of one or more analog or digital signals. In example implementations, the detected sound S_(D) may be composed of a plurality signals associated with respective channels 762 that are fed to the VCC 760.

Each channel 762 may correspond to a particular microphone 722. For example, an NMD having six microphones may have six corresponding channels. Each channel of the detected sound S_(D) may bear certain similarities to the other channels but may differ in certain regards, which may be due to the position of the given channel's corresponding microphone relative to the microphones of other channels. For example, one or more of the channels of the detected sound S_(D) may have a greater signal to noise ratio (“SNR”) of speech to background noise than other channels.

As further shown in FIG. 7C, the VCC 760 includes an AEC 763, a spatial processor 764, and one or more buffers 768. In operation, the AEC 763 receives the detected sound S_(D) and filters or otherwise processes the sound to suppress echoes and/or to otherwise improve the quality of the detected sound S_(D). That processed sound may then be passed to the spatial processor 764.

The spatial processor 764 is typically configured to analyze the detected sound S_(D) and identify certain characteristics, such as a sound's amplitude (e.g., decibel level), frequency spectrum, directionality, etc. In one respect, the spatial processor 764 may help filter or suppress ambient noise in the detected sound S_(D) from potential user speech based on similarities and differences in the constituent channels 762 of the detected sound S_(D), as discussed above. As one possibility, the spatial processor 764 may monitor metrics that distinguish speech from other sounds. Such metrics can include, for example, energy within the speech band relative to background noise and entropy within the speech band—a measure of spectral structure—which is typically lower in speech than in most common background noise. In some implementations, the spatial processor 764 may be configured to determine a speech presence probability, examples of such functionality are disclosed in U.S. patent application Ser. No. 15/984,073, filed May 18, 2018, titled “Linear Filtering for Noise-Suppressed Speech Detection,” which is incorporated herein by reference in its entirety.

In operation, the one or more buffers 768—one or more of which may be part of or separate from the memory 713 (FIG. 7A)—capture data corresponding to the detected sound S_(D). More specifically, the one or more buffers 768 capture detected-sound data that was processed by the upstream AEC 764 and spatial processor 766.

The network interface 724 may then provide this information to a remote server that may be associated with the MPS 100. In one aspect, the information stored in the additional buffer 769 does not reveal the content of any speech but instead is indicative of certain unique features of the detected sound itself. In a related aspect, the information may be communicated between computing devices, such as the various computing devices of the MPS 100, without necessarily implicating privacy concerns. In practice, the MPS 100 can use this information to adapt and fine-tune voice processing algorithms, including sensitivity tuning as discussed below. In some implementations the additional buffer may comprise or include functionality similar to lookback buffers disclosed, for example, in U.S. patent application Ser. No. 15/989,715, filed May 25, 2018, titled “Determining and Adapting to Changes in Microphone Performance of Playback Devices”; U.S. patent application Ser. No. 16/141,875, filed Sep. 25, 2018, titled “Voice Detection Optimization Based on Selected Voice Assistant Service”; and U.S. patent application Ser. No. 16/138,111, filed Sep. 21, 2018, titled “Voice Detection Optimization Using Sound Metadata,” which are incorporated herein by reference in their entireties.

In any event, the detected-sound data forms a digital representation (i.e., sound-data stream), S_(DS), of the sound detected by the microphones 720. In practice, the sound-data stream S_(DS) may take a variety of forms. As one possibility, the sound-data stream S_(DS) may be composed of frames, each of which may include one or more sound samples. The frames may be streamed (i.e., read out) from the one or more buffers 768 for further processing by downstream components, such as the VAS wake-word engines 770 and the voice extractor 773 of the NMD 703.

In some implementations, at least one buffer 768 captures detected-sound data utilizing a sliding window approach in which a given amount (i.e., a given window) of the most recently captured detected-sound data is retained in the at least one buffer 768 while older detected-sound data is overwritten when it falls outside of the window. For example, at least one buffer 768 may temporarily retain 20 frames of a sound specimen at given time, discard the oldest frame after an expiration time, and then capture a new frame, which is added to the 19 prior frames of the sound specimen.

In practice, when the sound-data stream S_(DS) is composed of frames, the frames may take a variety of forms having a variety of characteristics. As one possibility, the frames may take the form of audio frames that have a certain resolution (e.g., 16 bits of resolution), which may be based on a sampling rate (e.g., 44,100 Hz). Additionally, or alternatively, the frames may include information corresponding to a given sound specimen that the frames define, such as metadata that indicates frequency response, power input level, SNR, microphone channel identification, and/or other information of the given sound specimen, among other examples. Thus, in some embodiments, a frame may include a portion of sound (e.g., one or more samples of a given sound specimen) and metadata regarding the portion of sound. In other embodiments, a frame may only include a portion of sound (e.g., one or more samples of a given sound specimen) or metadata regarding a portion of sound.

In any case, downstream components of the NMD 703 may process the sound-data stream S_(DS) For instance, the VAS wake-word engines 770 are configured to apply one or more identification algorithms to the sound-data stream S_(DS) (e.g., streamed sound frames) to spot potential wake words in the detected-sound S_(D). This process may be referred to as automatic speech recognition. The VAS wake-word engine 770 a and local wake-word engine 771 apply different identification algorithms corresponding to their respective wake words, and further generate different events based on detecting a wake word in the detected-sound S_(D).

Example wake word detection algorithms accept audio as input and provide an indication of whether a wake word is present in the audio. Many first- and third-party wake word detection algorithms are known and commercially available. For instance, operators of a voice service may make their algorithm available for use in third-party devices. Alternatively, an algorithm may be trained to detect certain wake-words.

For instance, when the VAS wake-word engine 770 a detects a potential VAS wake word, the VAS work-word engine 770 a provides an indication of a “VAS wake-word event” (also referred to as a “VAS wake-word trigger”). In the illustrated example of FIG. 7A, the VAS wake-word engine 770 a outputs a signal S_(VW) that indicates the occurrence of a VAS wake-word event to the voice extractor 773.

In multi-VAS implementations, the NMD 703 may include a VAS selector 774 (shown in dashed lines) that is generally configured to direct extraction by the voice extractor 773 and transmission of the sound-data stream S_(DS) to the appropriate VAS when a given wake-word is identified by a particular wake-word engine (and a corresponding wake-word trigger), such as the VAS wake-word engine 770 a and at least one additional VAS wake-word engine 770 b (shown in dashed lines). In such implementations, the NMD 703 may include multiple, different VAS wake-word engines and/or voice extractors, each supported by a respective VAS.

Similar to the discussion above, each VAS wake-word engine 770 may be configured to receive as input the sound-data stream S_(DS) from the one or more buffers 768 and apply identification algorithms to cause a wake-word trigger for the appropriate VAS. Thus, as one example, the VAS wake-word engine 770 a may be configured to identify the wake word “Alexa” and cause the NMD 703 a to invoke the AMAZON VAS when “Alexa” is spotted. As another example, the wake-word engine 770 b may be configured to identify the wake word “Ok, Google” and cause the NMD 520 to invoke the GOOGLE VAS when “Ok, Google” is spotted. In single-VAS implementations, the VAS selector 774 may be omitted.

In response to the VAS wake-word event (e.g., in response to the signal S_(VW) indicating the wake-word event), the voice extractor 773 is configured to receive and format (e.g., packetize) the sound-data stream S_(DS). For instance, the voice extractor 773 packetizes the frames of the sound-data stream S_(DS) into messages. The voice extractor 773 transmits or streams these messages, M_(V), that may contain voice input in real time or near real time to a remote VAS via the network interface 724.

In some implementations, a user may selectively enable or disable voice input processing via cloud-based voice assistant services. In some examples, to disable the voice input processing via cloud-based voice assistant services, the NMD 703 physically or logically disables the VAS wake-word engine(s) 770. For instance, the NMD 703 may physically or logically prevent the sound-data stream S_(DS) from the microphones 722 from reaching the VAS wake-word engine(s) 770 and/or voice extractor 773. Suppressing generation may involve gating, blocking or otherwise preventing output from the VAS wake-word engine(s) 770 from generating a VAS wake-word event.

As described in connection with FIG. 2C, the voice input 780 may include a keyword portion and an utterance portion. The keyword portion may correspond to detected sound that causes a VAS wake-word event (i.e., a VAS wake word). Alternatively, the keyword portion may correspond to a local wake word or a command keyword, which may generate a local wake-word event.

For instance, when the voice input 780 includes a VAS wake word, the keyword portion corresponds to detected sound that causes the wake-word engine 770 a to output the wake-word event signal S_(VW) to the voice extractor 773. The utterance portion in this case corresponds to detected sound that potentially comprises a user request following the keyword portion.

When a VAS wake-word event occurs, the VAS may first process the keyword portion within the sound-data stream S_(DS) to verify the presence of a VAS wake word. In some instances, the VAS may determine that the keyword portion comprises a false wake word (e.g., the word “Election” when the word “Alexa” is the target VAS wake word). In such an occurrence, the VAS may send a response to the NMD 703 with an instruction for the NMD 703 to cease extraction of sound data, which causes the voice extractor 773 to cease further streaming of the detected-sound data to the VAS. The VAS wake-word engine 770 a may resume or continue monitoring sound specimens until it spots another potential VAS wake word, leading to another VAS wake-word event. In some implementations, the VAS does not process or receive the keyword portion but instead processes only the utterance portion.

In any case, the VAS processes the utterance portion to identify the presence of any words in the detected-sound data and to determine an underlying intent from these words. The words may correspond to one or more commands, as well as certain keywords. The keyword may be, for example, a word in the voice input identifying a particular device or group in the MPS 100. For instance, in the illustrated example, the keyword may be one or more words identifying one or more zones in which the music is to be played, such as the Living Room and the Dining Room (FIG. 1A).

To determine the intent of the words, the VAS is typically in communication with one or more databases associated with the VAS (not shown) and/or one or more databases (not shown) of the MPS 100. Such databases may store various user data, analytics, catalogs, and other information for natural language processing and/or other processing. In some implementations, such databases may be updated for adaptive learning and feedback for a neural network based on voice-input processing. In some cases, the utterance portion may include additional information such as detected pauses (e.g., periods of non-speech) between words spoken by a user, as shown in FIG. 2C. The pauses may demarcate the locations of separate commands, keywords, or other information spoke by the user within the utterance portion.

After processing the voice input, the VAS may send a response to the MPS 100 with an instruction to perform one or more actions based on an intent it determined from the voice input. For example, based on the voice input, the VAS may direct the MPS 100 to initiate playback on one or more of the playback devices 102, control one or more of these playback devices 102 (e.g., raise/lower volume, group/ungroup devices, etc.), or turn on/off certain smart devices, among other actions. After receiving the response from the VAS, the wake-word engine 770 a of the NMD 703 may resume or continue to monitor the sound-data stream S_(DS1) until it spots another potential wake-word, as discussed above.

In general, the one or more identification algorithms that a particular VAS wake-word engine, such as the VAS wake-word engine 770 a, applies are configured to analyze certain characteristics of the detected sound stream S_(DS1) and compare those characteristics to corresponding characteristics of the particular VAS wake-word engine's one or more particular VAS wake words. For example, the wake-word engine 770 a may apply one or more identification algorithms to spot spectral characteristics in the detected sound stream S_(DS) that match the spectral characteristics of the engine's one or more wake words, and thereby determine that the detected sound S_(D) comprises a voice input including a particular VAS wake word.

In some implementations, the one or more identification algorithms may be third-party identification algorithms (i.e., developed by a company other than the company that provides the NMD 703 a). For instance, operators of a voice service (e.g., AMAZON) may make their respective algorithms (e.g., identification algorithms corresponding to AMAZON's ALEXA) available for use in third-party devices (e.g., the NMDs 103), which are then trained to identify one or more wake words for the particular voice assistant service. Additionally, or alternatively, the one or more identification algorithms may be first-party identification algorithms that are developed and trained to identify certain wake words that are not necessarily particular to a given voice service. Other possibilities also exist.

As noted above, the NMD 703 a also includes a local wake-word engine 771 in parallel with the VAS wake-word engine 770 a. Like the VAS wake-word engine 770 a, the local wake-word engine 771 may apply one or more identification algorithms corresponding to one or more wake words. A “local wake-word event” is generated when a particular local wake-word is identified in the detected-sound S_(D). Local wake-words may take the form of a nonce wake word corresponding to local processing (e.g,. “Hey Sonos”), which is different from the VAS wake words corresponding to respective voice assistant services. Exemplary local wake-word detection is described in “Efficient keyword spotting using dilated convolutions and gating,” by Alice Coucke et al., published on Nov. 18, 2018, available at https://arxiv.org/pdf/1805.10190.pdf, which is incorporated by reference herein in its entirety.

Local keywords may also take the form of command keywords. In contrast to the nonce words typically as utilized as VAS wake words, command keywords function as both the activation word and the command itself. For instance, example command keywords may correspond to playback commands (e.g., “play,” “pause,” “skip,” etc.) as well as control commands (“turn on”), among other examples. Under appropriate conditions, based on detecting one of these command keywords, the NMD 703 a performs the corresponding command. Examples command keyword eventing is described in U.S. patent application Ser. No. 16/439,009, filed Jun. 12, 2019, titled “Network Microphone Device with Command Keyword Conditioning,” and available at https://arxiv.org/pdf/1811.07684v2.pdf, which is incorporated by reference in its entirety.

When a local wake-word event is generated, the NMD 703 can employ an automatic speech recognizer 775. The ASR 775 is configured to output phonetic or phenomic representations, such as text corresponding to words, based on sound in the sound-data stream S_(DS) to text. For instance, the ASR 775 may transcribe spoken words represented in the sound-data stream S_(DS) to one or more strings representing the voice input 780 as text. The ASR 775 can feed ASR output (labeled as S_(ASR)) to a local natural language unit (NLU) 776 that identifies particular keywords as being local keywords for invoking local-keyword events, as described below. Exemplary automatic speech recognition is described in “Snips Voice Platform: an embedded Spoken Language Understanding system for private-by-design voice interfaces,” by Alice Coucke et al., published on May 25, 2018, and available at https://arxiv.org/pdf/1805.10190.pdf, which is incorporated by reference herein in its entirety.

As noted above, in some example implementations, the NMD 703 is configured to perform natural language processing, which may be carried out using an onboard natural language processor, referred to herein as a natural language unit (NLU) 776. The local NLU 776 is configured to analyze text output of the ASR 775 to spot (i.e., detect or identify) keywords in the voice input 780. In FIG. 7A, this output is illustrated as the signal S_(ASR). The local NLU 776 includes a keyword library 778 (i.e., words and phrases) corresponding to respective commands and/or parameters.

In one aspect, the library 778 of the local NLU 776 includes local keywords, which, as noted above, may take the form of commands and parameters. The local NLU 776 may determine an underlying intent from the matched keywords in the voice input 780. For instance, if the local NLU matches the keywords “David Bowie” and “kitchen” in combination with a play command, the local NLU 776 may determine an intent of playing David Bowie in the Kitchen 101 h on the playback device 102 i. In contrast to a processing of the voice input 780 by a cloud-based VAS, local processing of the voice input 780 by the local NLU 776 may be relatively less sophisticated, as the NLU 776 does not have access to the relatively greater processing capabilities and larger voice databases that a VAS generally has access to.

In some examples, the local NLU 776 may determine an intent with one or more slots, which correspond to respective keywords. For instance, referring back to the play David Bowie in the Kitchen example, when processing the voice input, the local NLU 776 may determine that an intent is to play music (e.g., intent=playMusic), while a first slot includes David Bowie as target content (e.g., slot1=DavidBowie) and a second slot includes the Kitchen 101 h as the target playback device (e.g., slot2=kitchen). Here, the intent (to “playMusic”) is based on the command keyword and the slots are parameters modifying the intent to a particular target content and playback device.

Within examples, the wake-word engine 771, the ASR 775, and/or the NLU 776, referred to together as a local voice input pipeline 777 or, alternatively, a local keyword engine, may operate in one of a first mode and a second mode, which are referred to herein as a set-up mode and an operating mode, respectively. Initially (e.g., in when first powered-on or in a factory reset state), the local voice input pipeline 777 may operate in the set-up mode. In the set-up mode, the local NLU 776 may enable a portion of the keywords in the local natural language unit library 778 which may be provided as inputs during set-up. The set-up mode facilities voice-based set-up of the NMD 703, which may include set-up of one or more VAS(s).

After set-up, the local voice input pipeline 777 may transition to operating in the operating mode. In some examples, the local voice input pipeline 777 transitions to the operating mode automatically (e.g., after set-up is complete). Alternatively, the local voice input pipeline 777 transitions to the operating mode when local voice input processing is enabled. Yet further, in some instances, such as if the user 123 opts not to enable local voice input processing, the local voice input pipeline 777 may remain in the set-up mode, which allows the local voice input pipeline 777 to assist in troubleshooting or further set-up.

As noted above, the local voice input pipeline 777 may transition to the operating mode when local voice input processing is enabled. Enabling local voice input processing may be referred to herein as “adopting” the local voice input pipeline 777. In the operating mode, the local NLU 776 may enable additional keywords, such as those related to device control. Further, as discussed in more detail below, the local NLU 776 may enable custom keywords related to the user 123, such as device names, playlists, and other keywords that are unique to the media playback system 100.

Some error in performing local automatic speech recognition is expected. Within examples, the ASR 775 may generate a confidence score when transcribing spoken words to text, which indicates how closely the spoken words in the voice input 780 matches the sound patterns for that word. In some implementations, generating a local keyword event is based on the confidence score for a given local keyword. For instance, the local wake word engine 771 may generate a local wake word event when the confidence score for a given sound exceeds a given threshold value (e.g., 0.5 on a scale of 0-1, indicating that the given sound is more likely than not a local wake word). Conversely, when the confidence score for a given sound is at or below the given threshold value, the local wake-word engine 771 does not generate the local wake word event.

Similarly, some error in performing keyword matching is expected. Within examples, the local NLU 776 may generate a confidence score when determining an intent, which indicates how closely the transcribed words in the signal S_(ASR) match the corresponding keywords in the library 778 of the local NLU 776. In some implementations, performing an operation according to a determined intent is based on the confidence score for keywords matched in the signal S_(ASR). For instance, the NMD 703 may perform an operation according to a determined intent when the confidence score for a given sound exceeds a given threshold value (e.g., 0.5 on a scale of 0-1, indicating that the given sound is more likely than not the command keyword). Conversely, when the confidence score for a given intent is at or below the given threshold value, the NMD 703 does not perform the operation according to the determined intent.

As noted above, in some implementations, a phrase may be used as a local keyword, which provides additional syllables to match (or not match). For instance, the phrase “Hey, Sonos” has more syllables than “Sonos,” which provides additional sound patterns to match to words. As another example, the phrase “play me some music” has more syllables than “play,” which provides additional sound patterns to match to words. Accordingly, local keywords that are phrases may generally be less prone to false wake words.

In example implementations, the NMD 703 generates a local wake-word event based on a local keyword being detected only when certain conditions corresponding to a detected local keyword are met. These conditions are intended to lower the prevalence of false positive local keyword events. For instance, after detecting the command keyword “skip,” the NMD 703 generates a command keyword event (and skips to the next track) only when certain playback conditions indicating that a skip should be performed are met. These playback conditions may include, for example, (i) a first condition that a media item is being played back, (ii) a second condition that a queue is active, and (iii) a third condition that the queue includes a media item subsequent to the media item being played back. If any of these conditions are not satisfied, the command keyword event is not generated (and no skip is performed).

The NMD 703 may include one or more state machine(s) 779 to facilitate determining whether the appropriate conditions are met. An example state machine 779 a transitions between a first state and a second state based on whether one or more conditions corresponding to the detected command keyword are met. In particular, for a given command keyword corresponding to a particular command requiring one or more particular conditions, the state machine 779 a transitions into a first state when one or more particular conditions are satisfied and transitions into a second state when at least one condition of the one or more particular conditions is not satisfied.

Within example implementations, the command conditions are based on states indicated in state variables. As noted above, the devices of the MPS 100 may store state variables describing the state of the respective device. For instance, the playback devices 102 may store state variables indicating the state of the playback devices 102, such as the audio content currently playing (or paused), the volume levels, network connection status, and the like). These state variables are updated (e.g., periodically, or based on an event (i.e., when a state in a state variable changes)) and the state variables further can be shared among the devices of the MPS 100, including the NMD 703.

Similarly, the NMD 703 may maintain these state variables (either by virtue of being implemented in a playback device or as a stand-alone NMD). The state machine(s) 779 monitor the states indicated in these state variables, and determines whether the states indicated in the appropriate state variables indicate that the command condition(s) are satisfied. Based on these determinations, the state machines 779 transition between the first state and the second state, as described above.

In some implementations, the local wake word engine 771 is disabled unless certain conditions have been met via the state machines 779. For example, the first state and the second state of the state machine 779 a may operate as enable/disable toggles to the local wake word engine 771. In particular, while a state machine 779 a corresponding to a particular command keyword is in the first state, the state machine 779 a enables the local wake word engine 771 for the particular command keyword. Conversely, while the state machine 779 a corresponding to the particular command keyword is in the second state, the state machine 779 a disables the local wake-word engine 771 for the particular command keyword. Accordingly, the disabled local voice input pipeline 777 ceases analyzing the sound-data stream S_(DS).

Other example conditions may be based on the output of a voice activity detector (“VAD”) 765. The VAD 765 is configured to detect the presence (or lack thereof) of voice activity in the sound-data stream S_(DS). In particular, the VAD 765 may analyze frames corresponding to the pre-roll portion of the voice input 780 (FIG. 2D) with one or more voice detection algorithms to determine whether voice activity was present in the environment in certain time windows prior to a keyword portion of the voice input 780.

The VAD 765 may utilize any suitable voice activity detection algorithms. Example voice detection algorithms involve determining whether a given frame includes one or more features or qualities that correspond to voice activity, and further determining whether those features or qualities diverge from noise to a given extent (e.g., if a value exceeds a threshold for a given frame). Some example voice detection algorithms involve filtering or otherwise reducing noise in the frames prior to identifying the features or qualities.

In some examples, the VAD 765 may determine whether voice activity is present in the environment based on one or more metrics. For example, the VAD 765 can be configured distinguish between frames that include voice activity and frames that don't include voice activity. The frames that the VAD determines have voice activity may be caused by speech regardless of whether it near- or far-field. In this example and others, the VAD 765 may determine a count of frames in the pre-roll portion of the voice input 780 that indicate voice activity. If this count exceeds a threshold percentage or number of frames, the VAD 765 may be configured to output a signal or set a state variable indicating that voice activity is present in the environment. Other metrics may be used as well in addition to, or as an alternative to, such a count.

The presence of voice activity in an environment may indicate that a voice input is being directed to the NMD 703. Accordingly, when the VAD 765 indicates that voice activity is not present in the environment (perhaps as indicated by a state variable set by the VAD 765) this may be configured as one of the command conditions for the local keywords. When this condition is met (i.e., the VAD 765 indicates that voice activity is present in the environment), the state machine 779 a will transition to the first state to enable performing commands based on local keywords, so long as any other conditions for a particular local keyword are satisfied.

Further, in some implementations, the NMD 703 may include a noise classifier 766. The noise classifier 766 is configured to determine sound metadata (frequency response, signal levels, etc.) and identify signatures in the sound metadata corresponding to various noise sources. The noise classifier 766 may include a neural network or other mathematical model configured to identify different types of noise in detected sound data or metadata. One classification of noise may be speech (e.g., far-field speech). Another classification, may be a specific type of speech, such as background speech, and example of which is described in greater detail with reference to FIG. 8. Background speech may be differentiated from other types of voice-like activity, such as more general voice activity (e.g., cadence, pauses, or other characteristics) of voice-like activity detected by the VAD 765.

For example, analyzing the sound metadata can include comparing one or more features of the sound metadata with known noise reference values or a sample population data with known noise. For example, any features of the sound metadata such as signal levels, frequency response spectra, etc. can be compared with noise reference values or values collected and averaged over a sample population. In some examples, analyzing the sound metadata includes projecting the frequency response spectrum onto an eigenspace corresponding to aggregated frequency response spectra from a population of NMDs. Further, projecting the frequency response spectrum onto an eigenspace can be performed as a pre-processing step to facilitate downstream classification.

In various embodiments, any number of different techniques for classification of noise using the sound metadata can be used, for example machine learning using decision trees, or Bayesian classifiers, neural networks, or any other classification techniques. Alternatively or additionally, various clustering techniques may be used, for example K-Means clustering, mean-shift clustering, expectation-maximization clustering, or any other suitable clustering technique. Techniques to classify noise may include one or more techniques disclosed in U.S. application Ser. No. 16/227,308 filed Dec. 20, 2018, and titled “Optimization of Network Microphone Devices Using Noise Classification,” which is herein incorporated by reference in its entirety.

In some implementations, the additional buffer 769 (shown in dashed lines) may store information (e.g., metadata or the like) regarding the detected sound S_(D) that was processed by the upstream AEC 763 and spatial processor 764. This additional buffer 769 may be referred to as a “sound metadata buffer.” Examples of such sound metadata include: (1) frequency response data, (2) echo return loss enhancement measures, (3) voice direction measures; (4) arbitration statistics; and/or (5) speech spectral data. In example implementations, the noise classifier 766 may analyze the sound metadata in the buffer 769 to classify noise in the detected sound S_(D).

As noted above, one classification of sound may be background speech, such as speech indicative of far-field speech and/or speech indicative of a conversation not involving the NMD 703. The noise classifier 766 may output a signal and/or set a state variable indicating that background speech is present in the environment. The presence of voice activity (i.e., speech) in the pre-roll portion of the voice input 780 indicates that the voice input 780 might not be directed to the NMD 703, but instead be conversational speech within the environment. For instance, a household member might speak something like “our kids should have a play date soon” without intending to direct the command keyword “play” to the NMD 703.

Further, when the noise classifier indicates that background speech is present is present in the environment, this condition may disable the local voice input pipeline 777. In some implementations, the condition of background speech being absent in the environment (perhaps as indicated by a state variable set by the noise classifier 766) is configured as one of the command conditions for the command keywords. Accordingly, the state machine 779 a will not transition to the first state when the noise classifier 766 indicates that background speech is present in the environment.

Further, the noise classifier 766 may determine whether background speech is present in the environment based on one or more metrics. For example, the noise classifier 766 may determine a count of frames in the pre-roll portion of the voice input 780 that indicate background speech. If this count exceeds a threshold percentage or number of frames, the noise classifier 766 may be configured to output the signal or set the state variable indicating that background speech is present in the environment. Other metrics may be used as well in addition to, or as an alternative to, such a count.

Within example implementations, the NMD 703 a may support a plurality of local wake-words. To facilitate such support, the local wake-word engine 771 may implement multiple identification algorithms corresponding to respective local wake-words. Yet further, the library 778 of the local NLU 776 may include a plurality of local keywords and be configured to search for text patterns corresponding to these command keywords in the signal S_(ASR).

Referring still to FIG. 7B, in example embodiments, the VAS wake-word engine 770 a and the local voice input pipeline 777 may take a variety of forms. For example, the VAS wake-word engine 770 a and the local voice input pipeline 777 may take the form of one or more modules that are stored in memory of the NMD 703 (e.g., the memory 713 of FIG. 7A). As another example, the VAS wake-word engine 770 a and the local voice input pipeline 777 may take the form of a general-purposes or special-purpose processor, or modules thereof. In this respect, the wake-word engine 770 a and local voice input pipeline 777 may be part of the same component of the NMD 703 or each of the wake-word engine 770 a and the local voice input pipeline 777 may take the form of a dedicated component. Other possibilities also exist.

In some implementations, voice input processing via a cloud-based VAS and local voice input processing are concurrently enabled. A user may speak a local wake-word to invoke local processing of a voice input 780 b via the local voice input pipeline 777. Notably, even in the second mode, the NMD 703 may forego sending any data representing the detected sound S_(D) (e.g., the messages M_(v)) to a VAS when processing a voice input 780 b including a local wake word. Rather, the voice input 780 b is processed locally using the local voice input pipeline 777. Accordingly, speaking a voice input 780 b (with a local keyword) to the NMD 703 may provide increased privacy relative to other NMDs that process all voice inputs using a VAS.

As indicated above, some keywords in the library 778 of the local NLU 776 correspond to parameters. These parameters may define to perform the command corresponding to a detected command keyword. When keywords are recognized in the voice input 780, the command corresponding to the detected command keyword is performed according to parameters corresponding to the detected keywords.

For instance, an example voice input 780 may be “play music at low volume” with “play” being the command keyword portion (corresponding to a playback command) and “music at low volume” being the voice utterance portion. When analyzing this voice input 780, the NLU 776 may recognize that “low volume” is a keyword in its library 778 corresponding to a parameter representing a certain (low) volume level. Accordingly, the NLU 776 may determine an intent to play at this lower volume level. Then, when performing the playback command corresponding to “play,” this command is performed according to the parameter representing a certain volume level.

In a second example, another example voice input 780 may be “play my favorites in the Kitchen” with “play” again being the command keyword portion (corresponding to a playback command) and “my favorites in the Kitchen” as the voice utterance portion. When analyzing this voice input 780, the NLU 776 may recognize that “favorites” and “Kitchen” match keywords in its library 778. In particular, “favorites” corresponds to a first parameter representing particular audio content (i.e., a particular playlist that includes a user's favorite audio tracks) while “Kitchen” corresponds to a second parameter representing a target for the playback command (i.e., the kitchen 101 h zone. Accordingly, the NLU 776 may determine an intent to play this particular playlist in the kitchen 101 h zone.

In a third example, a further example voice input 780 may be “volume up” with “volume” being the command keyword portion (corresponding to a volume adjustment command) and “up” being the voice utterance portion. When analyzing this voice input 780, the NLU 776 may recognize that “up” is a keyword in its library 778 corresponding to a parameter representing a certain volume increase (e.g., a 10 point increase on a 100 point volume scale). Accordingly, the NLU 776 may determine an intent to increase volume. Then, when performing the volume adjustment command corresponding to “volume,” this command is performed according to the parameter representing the certain volume increase.

Other example voice inputs may relate to smart device commands. For instance, an example voice input 780 may be “turn on patio lights” with “turn on” being the command keyword portion (corresponding to a power on command) and “patio lights” being the voice utterance portion. When analyzing this voice input 780, the NLU 776 may recognize that “patio” is a keyword in its library 778 corresponding to a first parameter representing a target for the smart device command (i.e., the patio 101 i zone) and “lights” is a keyword in its library 778 corresponding to a second parameter representing certain class of smart device (i.e., smart illumination devices, or “smart lights”) in the patio 101 i zone. Accordingly, the NLU 776 may determine an intent to turn on smart lights associated with the patio 101 i zone. As another example, another example voice input 780 may be “set temperature to 75” with “set temperature” being the command keyword portion (corresponding to a thermostat adjustment command) and “to 75” being the voice utterance portion. When analyzing this voice input 780, the NLU 776 may recognize that “to 75” is a keyword in its library 778 corresponding to a parameter representing a setting for the thermostat adjustment command. Accordingly, the NLU 776 may determine an intent to set a smart thermostat to 75 degrees.

Within examples, certain command keywords are functionally linked to a subset of the keywords within the library 778 of the local NLU 776, which may hasten analysis. For instance, the command keyword “skip” may be functionality linked to the keywords “forward” and “backward” and their cognates. Accordingly, when the command keyword “skip” is detected in a given voice input 780, analyzing the voice utterance portion of that voice input 780 with the local NLU 776 may involve determining whether the voice input 780 includes any keywords that match these functionally linked keywords (rather than determining whether the voice input 780 includes any keywords that match any keyword in the library 778 of the local NLU 776). Since vastly fewer keywords are checked, this analysis is relatively quicker than a full search of the library 778. By contrast, a nonce VAS wake word such as “Alexa” provides no indication as to the scope of the accompanying voice input.

Some commands may require one or more parameters, as such the command keyword alone does not provide enough information to perform the corresponding command. For example, the command keyword “volume” might require a parameter to specify a volume increase or decrease, as the intent of “volume” of volume alone is unclear. As another example, the command keyword “group” may require two or more parameters identifying the target devices to group.

Accordingly, in some example implementations, when a given local wake-word is detected in the voice input 780 by the local wake-word engine 771, the local NLU 776 may determine whether the voice input 780 includes keywords matching keywords in the library 778 corresponding to the required parameters. If the voice input 780 does include keywords matching the required parameters, the NMD 703 a proceeds to perform the command (corresponding to the given command keyword) according to the parameters specified by the keywords.

However, if the voice input 780 does include keywords matching the required parameters for the command, the NMD 703 a may prompt the user to provide the parameters. For instance, in a first example, the NMD 703 a may play an audible prompt such as “I've heard a command, but I need more information” or “Can I help you with something?” Alternatively, the NMD 703 a may send a prompt to a user's personal device via a control application (e.g., the software components 132 c of the control device(s) 104).

In further examples, the NMD 703 a may play an audible prompt customized to the detected command keyword. For instance, after detect a command keyword corresponding to a volume adjustment command (e.g., “volume”), the audible prompt may include a more specific request such as “Do you want to adjust the volume up or down?” As another example, for a grouping command corresponding to the command keyword “group,” the audible prompt may be “Which devices do you want to group?” Supporting such specific audible prompts may be made practicable by supporting a relatively limited number of command keywords (e.g., less than 100), but other implementations may support more command keywords with the trade-off of requiring additional memory and processing capability.

Within additional examples, when a voice utterance portion does not include keywords corresponding to one or more required parameters, the NMD 703 a may perform the corresponding command according to one or more default parameters. For instance, if a playback command does not include keywords indicating target playback devices 102 for playback, the NMD 703 a may default to playback on the NMD 703 a itself (e.g., if the NMD 703 a is implemented within a playback device 102) or to playback on one or more associated playback devices 102 (e.g., playback devices 102 in the same room or zone as the NMD 703 a). Further, in some examples, the user may configure default parameters using a graphical user interface (e.g., user interface 430) or voice user interface. For example, if a grouping command does not specify the playback devices 102 to group, the NMD 703 a may default to instructing two or more pre-configured default playback devices 102 to form a synchrony group. Default parameters may be stored in data storage (e.g., the memory 112 b (FIG. 1F)) and accessed when the NMD 703 a determines that keywords exclude certain parameters. Other examples are possible as well.

In some implementations, the NMD 703 a sends the voice input 780 to a VAS when the local NLU 776 is unable to process the voice input 780 (e.g., when the local NLU is unable to find matches to keywords in the library 778, or when the local NLU 776 has a low confidence score as to intent). In an example, to trigger sending the voice input 780, the NMD 703 a may generate a bridging event, which causes the voice extractor 773 to process the sound-data stream S_(D), as discussed above. That is, the NMD 703 a generates a bridging event to trigger the voice extractor 773 without a VAS wake-word being detected by the VAS wake-word engine 770 a (instead based on a command keyword in the voice input 780, as well as the NLU 776 being unable to process the voice input 780).

Before sending the voice input 780 to the VAS (e.g., via the messages M_(V)), the NMD 703 a may obtain confirmation from the user that the user acquiesces to the voice input 780 being sent to the VAS. For instance, the NMD 703 a may play an audible prompt to send the voice input to a default or otherwise configured VAS, such as “I'm sorry, I didn't understand that. May I ask Alexa?” In another example, the NMD 703 a may play an audible prompt using a VAS voice (i.e., a voice that is known to most users as being associated with a particular VAS), such as “Can I help you with something?” In such examples, generation of the bridging event (and trigging of the voice extractor 773) is contingent on a second affirmative voice input 780 from the user.

Within certain example implementations, while in the first mode, the local NLU 776 may process the signal S_(ASR) without necessarily a local wake-word event being generated by the local wake-word engine 771 (i.e., directly). That is, the automatic speech recognition 775 may be configured to perform automatic speech recognition on the sound-data stream S_(D), which the local NLU 776 processes for matching keywords without requiring a local wake-word event. If keywords in the voice input 780 are found to match keywords corresponding to a command (possibly with one or more keywords corresponding to one or more parameters), the NMD 703 a performs the command according to the one or more parameters.

Further, in such examples, the local NLU 776 may process the signal S_(ASR) directly only when certain conditions are met. In particular, in some embodiments, the local NLU 776 processes the signal S_(ASR) only when the state machine 779 a is in the first state. The certain conditions may include a condition corresponding to no background speech in the environment. An indication of whether background speech is present in the environment may come from the noise classifier 766. As noted above, the noise classifier 766 may be configured to output a signal or set a state variable indicating that far-field speech is present in the environment. Further, another condition may correspond to voice activity in the environment. The VAD 765 may be configured to output a signal or set a state variable indicating that voice activity is present in the environment. The prevalence of false positive detection of commands with a direct processing approach may be mitigated using the conditions determined by the state machine 779 a.

IV. Example Local Voice Data Processing

In some examples, the library 778 of the local NLU 776 is partially customized to the individual user(s). In a first aspect, the library 778 may be customized to the devices that are within the household of the NMD (e.g., the household within the environment 101 (FIG. 1A)). For instance, the library 778 of the local NLU may include keywords corresponding to the names of the devices within the household, such as the zone names of the playback devices 102 in the MPS 100. In a second aspect, the library 778 may be customized to the users of the devices within the household. For example, the library 778 of the local NLU 776 may include keywords corresponding to names or other identifiers of a user's preferred playlists, artists, albums, and the like. Then, the user may refer to these names or identifiers when directing voice inputs to the local voice input pipeline 777.

Within example implementations, the NMD 703 may populate the library 778 of the local NLU 776 locally within the network 111 (FIG. 1B). As noted above, the NMD 703 may maintain or have access to state variables indicating the respective states of devices connected to the network 111 (e.g., the playback devices 104). These state variables may include names of the various devices. For instance, the kitchen 101 h may include the playback device 101 b, which are assigned the zone name “Kitchen.” The NMD 703 may read these names from the state variables and include them in the library 778 of the local NLU 776 by training the local NLU 776 to recognize them as keywords. The keyword entry for a given name may then be associated with the corresponding device in an associated parameter (e.g., by an identifier of the device, such as a MAC address or IP address). The NMD 703 a can then use the parameters to customize control commands and direct the commands to a particular device.

In further examples, the NMD 703 may populate the library 778 by discovering devices connected to the network 111. For instance, the NMD 703 a may transmit discovery requests via the network 111 according to a protocol configured for device discovery, such as universal plug-and-play (UPnP) or zero-configuration networking. Devices on the network 111 may then respond to the discovery requests and exchange data representing the device names, identifiers, addresses and the like to facilitate communication and control via the network 111. The NMD 703 may read these names from the exchanged messages and include them in the library 778 of the local NLU 776 by training the local NLU 776 to recognize them as keywords.

In further examples, the NMD 703 may populate the library 778 using the cloud. To illustrate, FIG. 8 is a schematic diagram of the MPS 100 and a cloud network 802. The cloud network 802 includes cloud servers 806, identified separately as media playback system control servers 806 a, streaming audio service servers 806 b, and IOT cloud servers 806 c. The streaming audio service servers 806 b may represent cloud servers of different streaming audio services. Similarly, the IOT cloud servers 806 c may represent cloud servers corresponding to different cloud services supporting smart devices 880 in the MPS 100. Smart devices 880 include smart illumination devices, smart thermostats, smart plugs, security cameras, doorbells, and the like.

Within examples, a user may link an account of the MPS 100 to an account of an IOT service. For instance, an IOT manufacturer (such as IKEA®) may operate a cloud-based IOT service to facilitate cloud-based control of their IOT products using smartphone app, website portal, and the like. In connection with such linking, keywords associated with the cloud-based service and the IOT devices may be populated in the library 778 of the local NLU 776. For instance, the library 778 may be populated with a nonce keyword (e.g., “Hey Ikea”). Further, the library 778 may be populated with names of various IOT devices, keyword commands for controlling the IOT devices, and keywords corresponding to parameters for the commands.

One or more communication links 803 a, 803 b, and 803 c (referred to hereinafter as “the links 803”) communicatively couple the MPS 100 and the cloud servers 806. The links 803 can include one or more wired networks and one or more wireless networks (e.g., the Internet). Further, similar to the network 111 (FIG. 1B), a network 811 communicatively couples the links 803 and at least a portion of the devices (e.g., one or more of the playback devices 102, NMDs 103, control devices 104, and/or smart devices 880) of the MPS 100.

In some implementations, the media playback system control servers 806 a facilitate populating the library 778 of local NLU 776. In an example, the media playback system control servers 806 a may receive data representing a request to populate the library 778 of a local NLU 776 from the NMD 703 a. Based on this request, the media playback system control servers 806 a may communicate with the streaming audio service servers 806 b and/or IOT cloud servers 806 c to obtain keywords specific to the user.

In some examples, the media playback system control servers 806 a may utilize user accounts and/or user profiles in obtaining keywords specific to the user. As noted above, a user of the MPS 100 may set-up a user profile to define settings and other information within the MPS 100. The user profile may then in turn be registered with user accounts of one or more streaming audio services to facilitate streaming audio from such services to the playback devices 102 of the MPS 100.

Through use of these registered streaming audio services, the streaming audio service servers 806 b may collect data indicating a user's saved or preferred playlists, artists, albums, tracks, and the like, either via usage history or via user input (e.g., via a user input designating a media item as saved or a favorite). This data may be stored in a database on the streaming audio service servers 806 b to facilitate providing certain features of the streaming audio service to the user, such as custom playlists, recommendations, and similar features. Under appropriate conditions (e.g., after receiving user permission), the streaming audio service servers 806 b may share this data with the media playback system control servers 806 a over the links 803 b.

Accordingly, within examples, the media playback system control servers 806 a may maintain or have access to data indicating a user's saved or preferred playlists, artists, albums, tracks, genres, and the like. If a user has registered their user profile with multiple streaming audio services, the saved data may include saved playlists, artists, albums, tracks, and the like from two or more streaming audio services. Further, the media playback system control servers 806 a may develop a more complete understanding of the user's preferred playlists, artists, albums, tracks, and the like by aggregating data from the two or more streaming audio services, as compared with a streaming audio service that only has access to data generated through use of its own service.

Moreover, in some implementations, in addition to the data shared from the streaming audio service servers 806 b, the media playback system control servers 806 a may collect usage data from the MPS 100 over the links 803 a, after receiving user permission. This may include data indicating a user's saved or preferred media items on a zone basis. Different types of music may be preferred in different rooms. For instance, a user may prefer upbeat music in the Kitchen 101 h and more mellow music to assist with focus in the Office 101 e.

Using the data indicating a user's saved or preferred playlists, artists, albums, tracks, and the like, the media playback system control servers 806 a may identify names of playlists, artists, albums, tracks, and the like that the user is likely to refer to when providing playback commands to the NMDs 703 via voice input. Data representing these names can then be transmitted via the links 803 a and the network 804 to the NMDs 703 and then added to the library 778 of the local NLU 776 as keywords. For instance, the media playback system control servers 806 a may send instructions to the NMD 703 to include certain names as keywords in the library 778 of the local NLU 776. Alternatively, the NMD 703 (or another device of the MPS 100) may identify names of playlists, artists, albums, tracks, and the like that the user is likely to refer to when providing playback commands to the NMD 703 via voice input and then include these names in the library 778 of the local NLU 776.

Due to such customization, similar voice inputs may result in different operations being performed when the voice input is processed by the local NLU 776 as compared with processing by a VAS. For instance, a first voice input of “Alexa, play me my favorites in the Office” may trigger a VAS wake-word event, as it includes a VAS wake word (“Alexa”). A second voice input of “Play me my favorites in the Office” may trigger a command keyword, as it includes a command keyword (“play”). Accordingly, the first voice input is sent by the NMD 703 to the VAS, while the second voice input is processed by the local NLU 776.

While these voice inputs are nearly identical, they may cause different operations. In particular, the VAS may, to the best of its ability, determine a first playlist of audio tracks to add to a queue of the playback device 102 f in the office 101 e. Similarly, the local NLU 776 may recognize keywords “favorites” and “kitchen” in the second voice input. Accordingly, the NMD 703 performs the voice command of “play” with parameters of <favorites playlist> and <kitchen 101 h zone>, which causes a second playlist of audio tracks to be added to the queue of the playback device 102 f in the office 101 e. However, the second playlist of audio tracks may include a more complete and/or more accurate collection of the user's favorite audio tracks, as the second playlist of audio tracks may draw on data indicating a user's saved or preferred playlists, artists, albums, and tracks from multiple streaming audio services, and/or the usage data collected by the media playback system control servers 806 a. In contrast, the VAS may draw on its relatively limited conception of the user's saved or preferred playlists, artists, albums, and tracks when determining the first playlist.

A household may include multiple users. Two or more users may configure their own respective user profiles with the MPS 100. Each user profile may have its own user accounts of one or more streaming audio services associated with the respective user profile. Further, the media playback system control servers 806 a may maintain or have access to data indicating each user's saved or preferred playlists, artists, albums, tracks, genres, and the like, which may be associated with the user profile of that user.

In various examples, names corresponding to user profiles may be populated in the library 778 of the local NLU 776. This may facilitate referring to a particular user's saved or preferred playlists, artists, albums, tracks, or genres. For instance, when a voice input of “Play Anne's favorites on the patio” is processed by the local NLU 776, the local NLU 776 may determine that “Anne” matches a stored keyword corresponding to a particular user. Then, when performing the playback command corresponding to that voice input, the NMD 703 adds a playlist of that particular user's favorite audio tracks to the queue of the playback device 102 c in the patio 101 i.

In some cases, a voice input might not include a keyword corresponding to a particular user, but multiple user profiles are configured with the MPS 100. In some cases, the NMD 703 a may determine the user profile to use in performing a command using voice recognition. Alternatively, the NMD 703 a may default to a certain user profile. Further, the NMD 703 a may use preferences from the multiple user profiles when performing a command corresponding to a voice input that did not identify a particular user profile. For instance, the NMD 703 a may determine a favorites playlist including preferred or saved audio tracks from each user profile registered with the MPS 100.

The IOT cloud servers 806 c may be configured to provide supporting cloud services to the smart devices 880. The smart devices 880 may include various “smart” internet-connected devices, such as lights, thermostats, cameras, security systems, appliances, and the like. For instance, an IOT cloud server 806 c may provide a cloud service supporting a smart thermostat, which allows a user to control the smart thermostat over the internet via a smartphone app or website.

Accordingly, within examples, the IOT cloud servers 806 c may maintain or have access to data associated with a user's smart devices 880, such as device names, settings, and configuration. Under appropriate conditions (e.g., after receiving user permission), the IOT cloud servers 806 c may share this data with the media playback system control servers 806 a and/or the NMD 703 a via the links 803 c. For instance, the IOT cloud servers 806 c that provide the smart thermostat cloud service may provide data representing such keywords to the NMD 703, which facilitates populating the library 778 of the local NLU 776 with keywords corresponding to the temperature.

Yet further, in some cases, the IOT cloud servers 806 c may also provide keywords specific to control of their corresponding smart devices 880. For instance, the IOT cloud server 806 c that provides the cloud service supporting the smart thermostat may provide a set of keywords corresponding to voice control of a thermostat, such as “temperature,” “warmer,” or “cooler,” among other examples. Data representing such keywords may be sent to the NMDs 703 over the links 803 and the network 804 from the IOT cloud servers 806 c.

As noted above, some households may include more than NMD 703. In example implementations, two or more NMDs 703 may synchronize or otherwise update the libraries of their respective local NLU 776. For instance, a first NMD 703 a and a second NMD 703 b may share data representing the libraries of their respective local NLU 776, possibly using a network (e.g., the network 904). Such sharing may facilitate the NMDs 703 a being able to respond to voice input similarly, among other possible benefits.

In some embodiments, one or more of the components described above can operate in conjunction with the microphones 720 to detect and store a user's voice profile, which may be associated with a user account of the MPS 100. In some embodiments, voice profiles may be stored as and/or compared to variables stored in a set of command information or data table. The voice profile may include aspects of the tone or frequency of a user's voice and/or other unique aspects of the user, such as those described in previously-referenced U.S. patent application Ser. No. 15/438,749.

In some embodiments, one or more of the components described above can operate in conjunction with the microphones 720 to determine the location of a user in the home environment and/or relative to a location of one or more of the NMDs 103. Techniques for determining the location or proximity of a user may include one or more techniques disclosed in previously-referenced U.S. patent application Ser. No. 15/438,749, U.S. Pat. No. 9,084,058 filed Dec. 29, 2011, and titled “Sound Field Calibration Using Listener Localization,” and U.S. Pat. No. 8,965,033 filed Aug. 31, 2012, and titled “Acoustic Optimization.” Each of these applications is herein incorporated by reference in its entirety.

FIGS. 9A, 9B, 9C, and 9D show exemplary input and output from the NMD 703 configured in accordance with aspects of the disclosure.

FIG. 9A illustrates a first scenario in which a wake-word engine of the NMD 703 is configured to detect four local wake-words (“play”, “stop”, “resume”, “Sonos”). The local NLU 776 (FIG. 7C) is disabled. In this scenario, the user has spoken the voice input “Hey, Sonos” to the NMD 703, which triggers a new recognition of one of the local wake-word.

Yet further, the VAD 765 and noise classifier 766 (FIG. 7C) have analyzed 150 frames of a pre-roll portion of the voice input. As shown, the VAD 765 has detected voice in 140 frames of the 150 pre-roll frames, which indicates that a voice input may be present in the detected sound. Further, the noise classifier 766 has detected ambient noise in 11 frames, background speech in 127 frames, and fan noise in 12 frames. In this example, the noise classifier 766 is classifying the predominant noise source in each frame. This indicates the presence of background speech. As a result, the NMD has determined not to trigger on the detected local keyword “Sonos.”

FIG. 9B illustrates a second scenario in which the local voice wake-word engine 771 of the NMD 703 is configured to detect a local keyword (“play”) as well as two cognates of that command keyword (“play something” and “play me a song”). The local NLU 776 is disabled. In this second scenario, the user has spoken the voice input “play something” to the NMD 703, which triggers a new recognition of one of the local keywords (e.g., a command keyword event).

Yet further, the VAD 765 and noise classifier 766 have analyzed 150 frames of a pre-roll portion of the voice input. As shown, the VAD 765 has detected voice in 87 frames of the 150 pre-roll frames, which indicates that a voice input may be present in the detected sound. Further, the noise classifier 766 has detected ambient noise in 18 frames, background speech in 8 frames, and fan noise in 124 frames. This indicates that background speech is not present. Given the foregoing, the NMD 703 has determined to trigger on the detected local keyword “play.”

FIG. 9C illustrates a third scenario in which the local wake-word engine 771 of the NMD 703 is configured to detect three local keywords (“play”, “stop”, and “resume”). The local NLU 776 is enabled. In this third scenario, the user has spoken the voice input “play Beatles in the Kitchen” to the NMD 703, which triggers a new recognition of one of the local keywords (e.g., a command keyword event corresponding to play).

As shown, the ASR 775 has transcribed the voice input as “play beet les in the kitchen.” Some error in performing ASR is expected (e.g., “beet les”). Here, the local NLU 776 has matched the keyword “beet les” to “The Beatles” in the local NLU library 778, which sets up this artist as a content parameter to the play command. Further, the local NLU 776 has also matched the keyword “kitchen” to “kitchen” in the local NLU library 778, which sets up the kitchen zone as a target parameter to the play command. The local NLU produced a confidence score of 0.63428231948273443 associated with the intent determination.

Here as well, the VAD 765 and noise classifier 766 have analyzed 150 frames of a pre-roll portion of the voice input. As shown, the noise classifier 766 has detected ambient noise in 142 frames, background speech in 8 frames, and fan noise in 0 frames. This indicates that background speech is not present. The VAD 765 has detected voice in 112 frames of the 150 pre-roll frames, which indicates that a voice input may be present in the detected sound. Here, the NMD 703 has determined to trigger on the detected command keyword “play.”

FIG. 9D illustrates a fourth scenario in which the local wake-word engine 771 of the NMD is not configured to spot any local keywords. Rather, the local wake-word engine 771 will perform ASR and pass the output of the ASR to the local NLU 776. The local NLU 776 is enabled and configured to detect keywords corresponding to both commands and parameters. In the fourth scenario, the user has spoken the voice input “play some music in the Office” to the NMD 703.

As shown, the ASR 775 has transcribed the voice input as “lay some music in the office.” Here, the local NLU 776 has matched the keyword “lay” to “play” in the local NLU library 778, which corresponds to a playback command. Further, the local NLU 776 has also matched the keyword “office” to “office” in the local NLU library 778, which sets up the office 101 e zone as a target parameter to the play command. The local NLU 776 produced a confidence score of 0.14620494842529297 associated with the keyword matching. In some examples, this low confidence score may cause the NMD to not accept the voice input (e.g., if this confidence score is below a threshold, such as 0.5).

V. Example Local Voice Data Processing Via Extensible Playback Device

An example media playback system includes one or more satellites and at least one hub device. For instance, an example system may include at least a first playback device (or satellite) and a second playback device (or hub device). In another example of such a hub-and-spoke architecture, example systems may include one or more microcontroller units (MCUs) as satellites and a playback device as the hub device. In the following sections, the term “satellite” is used to refer to relatively lesser-powered (in terms of processing power and memory) NMDs in the media playbacks system, such as the first playback device(s) and the MCU(s) while “hub” is used to refer to relatively higher-powered (in terms of processing power and memory) devices, such as the second playback device. Satellites and hub devices may include the same or similar components as the NMD 703.

An example satellite includes audio front-end components 1020 a, as shown in FIG. 10A. The audio front-end components 1020 a may include one or more microphones (e.g., the microphones 722 in FIG. 7A). In some examples, a far-field microphone array may form part of the audio front-end 1020 a. In other embodiments, a microphone configured for near-field detection may form part of the audio front-end 1020 a. In some examples, the audio front-end components 1020 a may include a spatial processor, an acoustic echo canceller (AEC), and/or other components for processing and filtering detected sound (which may be, for example, the same or similar to the VCC 760 (FIG. 7C)

The example satellite may also include onboard voice analysis components 1020 b, as further shown in FIG. 10A. The onboard voice analysis components 1020 b are configured to analyze voice inputs detected by the audio front-end 1020 a. The voice analysis components 1020 b include, for example, a wake word detector (which may be the same or similar to the VAS wake-word engine 770 a and/or the local wake-word engine 771). The voice analysis components 1020 b may also include automatic speech recognition components (which may be the same or similar to the ASR 775 in FIG. 7C) and/or natural language understanding components (which may be the same or similar to the local NLU 776 in FIG. 7C).

A. First Mode of Operation

In a first mode of operation, the satellite is configured to forward a voice utterance to a remote voice input processor, such as a cloud server, upon detecting a wake word (e.g., “Hey Sonos”) in the voice input. The cloud server is outside of the local network (e.g., LAN 111) of the media playback system, such as with the computing device(s) 106 a of the VAS 190 (FIG. 1B). In some example implementations, a particular wake word (e.g., Hey Sonos) may be associated with a context-based service, such as a Sonos voice assistant service which may provide media-playback-related and/or smart home-related services. In various examples, the satellite may perform some voice analysis locally, but may “fall back” to a more capable voice processer (e.g., the cloud or a hub) under certain conditions, as described in greater detail below.

B. Second Mode of Operation

In a second mode of operation in accordance with various embodiments of the disclosure, the satellite is configured to forward a voice utterance to a hub device. In some examples, the satellite may operate in the second mode when the hub device is joined to the media playback system. The hub device may be joined to the media playback system by connecting the hub device to the LAN 111 and/or configuring the hub device with a user profile. In the second mode of operation, after detecting a wake word, the first playback device forwards voice data representing the voice inputs to the hub device rather than to the cloud.

In various embodiments, the hub device can be a second playback device 1002, as shown in FIG. 10B. As further shown in FIG. 10B, in some examples, one or more other playback devices (or satellites) of the media playback system may be similarly configured to forward voice utterances to the hub device upon detecting a wake word. The one or more other playback devices are representative of various types of satellites, such as the MCUs noted above.

In some embodiments, the second playback device 1002 includes an audio front-end, such as an audio front-end similar to the audio frontend of the first playback device (FIG. 10A). Alternatively, in other examples, the audio front-end may be omitted from the second playback device. In still further embodiments, the hub device may be a specialized voice analysis device, which does not include hardware and/or software components to configure the hub device to operate as a playback device in addition to the hub device.

In any case, the hub device is configured to perform local spoken language understanding on voice inputs from the satellite playback devices, as well as voice inputs detected directly on the hub device. The hub device may include voice analysis components such as an ASR (automatic speech recognition) component, and a language modelling and understanding component, or “NLU”, as shown below in FIG. 10C. In some examples, these components may be similar to the components of the NMD 703 (FIG. 7B). In some cases, the hub device may include more capable processors 1012 and memory 1013 to enable relatively more sophisticated local voice processing as compared with the satellite device(s) (e.g., the playback device(s) 102 or the MCU(s)).

In operation, the NLU of the hub device may maintain a library of keywords and phrases that, when detected in utterance, are indicative of an intent (e.g., “play music”) and slots associated with the intent. For instance, the local NLU may be periodically updated with slot information corresponding to the names of a user's favorite tracks, albums, playlists, etc. Further details on such customization are discussed in connection with FIG. 9.

The hub device may be generally capable of determining the intent and slot information in a spoken utterance without transmitting the utterance to a remote cloud server. In such cases, the captured voice data is not transmitted outside of the local network of the media playback system. In other words, by adding a hub device to the media playback system, privacy is upgraded across the network, as the satellite devices are able to process voice inputs locally using the hub device.

In some cases, however, the hub device may be configured to fall back to the cloud for certain types of voice inputs. For instance, the hub device may fall back to the cloud for certain classes of queries that are not in the library of keywords and phrases and/or queries that rely on information from the Internet (e.g., what is the weather?). In examples, whether the hub device is configured to fall back to the cloud is user-configurable—that is the hub device may be prevented from falling back to the cloud when a certain setting is set to disable cloud fallback (i.e., when a user desires to keep all queries local) and allowed to fall back when that certain setting is set to enable cloud fallback. Such a setting may be set using various GUIs and VUIs described herein (e.g., the control interface on the control device(s) 104) or via a voice input to the hub device or satellite(s).

C. Satellite with Fallback

In some embodiments, the satellite(s) may include additional components configured for onboard voice analysis, such as an ASR component and NLU component. As noted above, the onboard voice analysis of the satellites may be relatively less capable than the hub device. Given this limitation, the set of keywords supported by satellites may be more tailored to certain contexts.

For example, the set of keywords supported by a satellite may include keywords corresponding to media playback commands. This may include a subset of keywords relative to the hub device. For instance, the satellites may support on-board recognition of certain keywords corresponding to transport control (e.g., “play”, “pause” “skip”), volume control (“turn it up” “turn it down” “mute), and/or grouping (“play back music on Living Room and Kitchen”). The hub device, by contrast, may support on-board recognition of keywords corresponding to a complete, or more complete set of media playback commands supported by the media playback system 100 (FIG. 1A).

Yet further, the NLU may alternatively or additionally support on-board recognition of certain keywords related to other contexts, such as control of a specific class of smart devices. For instance, a satellite, such as an MCU, may be embedded, implemented in, or otherwise associated with a smart device, such as a smart appliance. In such examples, the set of keywords supported by a satellite may include keywords corresponding to smart device commands. For example, an MCU implemented in a smart appliance (e.g., a smart microwave) may support keywords for controlling the smart appliance (e.g., “turn on for 30 seconds” “start defrost mode for 1.1 lbs”), among other examples. When the a satellite is associated with other types of smart devices (e.g., smart illumination devices, smart switches, smart cameras, etc), the satellite may be configured to support on-board recognition of keywords corresponding to those devices (perhaps in addition to media playback system commands). Notably, a satellite is not able or configured to support recognition of all of the keywords that a hub supports, much less able to process the wide variety of voice inputs that the cloud is able to successfully process.

When a hub is not joined to the media playback system, a satellite (e.g., the first playback device(s)) may “fall back” to the cloud when it cannot resolve particular slot information in an utterance, as shown in FIG. 10D. In such instances, the first playback device(s) 102 will fall back to the cloud only under certain conditions. For example, the first playback device(s) 102 may be configured to fall back to the cloud only when (i) the intent of the utterance has been detected by the onboard SLU and (ii) the detected intent pertains to the media playback domain. If these conditions are not satisfied, the first playback device(s) 102 will not send the utterance to the cloud.

With respect to the second condition, the cloud service invoked during cloud fallback may be a context-based service, such as a media playback related voice assistant service. In an effort to protect user privacy, utterances that have been determined locally to exclude keywords related to the specific content (e.g., transport control, content selection, and the like for media playback) are not transferred to the context-based service. Such implementations may contrast with a general VAS, which receives all utterances connected with a detected wake word.

In one aspect, the satellite may be de-coupled or otherwise disconnected from the cloud when the hub device is joined to the media playback system, as shown in FIG. 1 (above). This arrangement keeps voice inputs local (e.g., within the LAN 111). As noted above, by way of example, the second playback device 1002 may include substantial voice processing resources relative to those of the first playback device 102 to fully process voice inputs locally.

In some example implementations, once the hub device is joined to the media playback system, cloud fallback is disabled on all of the satellite devices of the media playback system. Accordingly, a user may be assured that their utterances are not being sent to the cloud, but are instead processed locally on their own network.

In some examples, when detecting an utterance, the satellite determines whether the utterance includes a media playback-related intent using on-board NLU. Since the satellite is designed to be less capable or incapable, the satellite does not resolve slot information in voice utterances.

Alternatively, in some cases, the satellite may have sufficient hardware and software components to process some voice inputs locally, but is configured to not utilize those components when operating as a satellite device. That is, the satellite may deactivate its local NLU and/or ASR when a hub device joins the media playback system. For instance, the satellite may transmit the output of the ASR component to the hub device and forego local NLU processing to conserve device resources.

In some embodiments, the satellite may perform basic local voice input recognition for certain user-specific information, which the user may consider more private. For instance, the NLU of the satellite may be configured to recognize a user's favorite artists, albums, songs, or playlists and then fallback to the cloud for recognition on large catalog from one or more streaming media service. Or, alternatively, as discussed above, the satellite may be configured with just have ability to recognize simple media playback system commands, like “play” or “pause” and not full natural language (“Play the Beatles on Living Room”). A more capable hub device, when added, may handle the user catalog in addition to the large catalogue locally. In this case, each satellite device will forward voice input to the hub, and the entire voice recognition and related processing is performed by the hub device.

D. Additional Examples

As an additional example, an experience of a home powered by a Sonos Music Assistant, relying on a blend of Sonos devices, powered by a microphone or not, on Sonos Voice Satellite devices, as well as third party Sonos certified speakers, is shown in FIG. 10E. In this example, a Sonos Beam is operating as a hub device, while all other Sonos and certified playback devices are operating as satellites.

As yet another example, Internet-of-Things (IOT) devices, such as lights, thermostats, appliances, entertainment devices, and other smart home devices may be supported by a satellite—hub implementation, such as a Sonos Home assistant, which may be in addition to a music voice assistant. A Sonos Home assistant may blend local home control interfaces into a coherent experience, as shown in the example of FIG. 10F. In this example, a Sonos Beam serves as a hub device, while all other IOT and playback devices are satellites.

In the Kitchen, a Sonos Satellite is associated with a smart appliance (an espresso machine). In accordance with above-described examples, this satellite may support on-board recognition of keywords corresponding to media playback system commands as well as context-specific keywords. The context-specific keywords may include keywords related to control of the associated smart appliance (e.g., brew double espresso).

V. Example Techniques

FIGS. 11A and 11B are a flow diagram showing an example method 1100 to capture and process voice inputs. The method 1100 may be performed by a system including a satellite device and a hub device. Alternatively, the method 1100 may be performed by any suitable device or by a system of devices, such as the playback devices 102, NMDs 103, control devices 104, computing devices 105 or computing devices 106. By way of illustration, certain portions of the method 1100 are described as being performed by a satellite device or a hub device. Example satellite devices include playback devices 102 and microcontroller units (MCUs), as described above, which may implement one or more of the components of the NMD 703 (FIGS. 7A-7C) to facilitate processing of voice inputs. As described above, an example hub devices is the second playback device 1002 (FIG. 10B), which similarly may implement the components of the NMD 703 to facilitate processing of voice inputs.

In FIG. 11A, at block 1102, the method 1100 involves storing, in memory, data representing a first set of local keywords. The first set of local keywords may include first keywords corresponding to one or more media playback system commands. For instance, as described above, a satellite may be configured to support on-board recognition of keywords corresponding to certain media playback system commands. The first set of local keywords may additionally or alternatively include second keywords corresponding to one or more smart device commands, such as one or more smart appliance commands. As noted above, satellite devices may include a context-specific set of keywords corresponding to an associated smart device or device(s).

At block 1104, the method 1100 involves capturing a first voice input. Capturing a voice input may involve the satellite recording voice data via one or more microphones (e.g., the microphones 722 of FIGS. 7A-7C) and buffering the voice data (e.g., in the buffers 768 of FIG. 7C). Capturing the voice input may further involve conditioning the voice data using an audio frontend (e.g., the VCC 760 of FIG. 7C).

At block 1106, the method 1100 involves determining that one or more uttered keywords in the captured first voice input are not in the first set of local keywords. For instance, the satellite may analyze the captured first voice input using voice analysis components (e.g., the local voice input pipeline 777) and determine that portions of the captured first voice input correspond to words that are not in the first set of local keywords. More particularly, the satellite may fail to match such portions of the captured first voice input to keywords in the first set of local keywords with high enough confidence (FIGS. 9A-9D) such that the satellite determines that one or more uttered keywords in the captured first voice input are not in the first set of local keywords.

At block 1108, the method 1100 involves sending data representing the first voice input to a hub device. In other words, the satellite may fall back to the hub device for processing of the first voice input. The satellite may send the data via a network interface (e.g., the network interface 724 (FIG. 7A)). The data representing the first voice input may be in the form of voice data from the buffers 768 (FIG. 7C), which may be conditioned by the audio frontend (e.g., the VCC 760 (FIG. 7C)).

At block 1110, the method 1100 involves capturing a second voice input. Capturing a voice input may involve the satellite recording additional voice data via one or more microphones (e.g., the microphones 722 of FIGS. 7A-7C) and buffering the additional voice data (e.g., in the buffers 768 of FIG. 7C). Capturing the voice input may further involve conditioning the additional voice data using an audio frontend (e.g., the VCC 760 of FIG. 7C).

At block 1112, the method 1100 involves processing the second voice input. For instance, the satellite may analyze the captured second voice input using voice analysis components (e.g., the local voice input pipeline 777) and determine that portions of the captured second voice input correspond to words that are in the first set of local keywords. More particularly, the satellite may match such portions of the captured second voice input to keywords in the first set of local keywords with high enough confidence (FIGS. 9A-9D) such that the satellite determines that one or more uttered keywords in the captured second voice input are in the first set of local keywords. The satellite may match portions of the second voice input to at least one particular first keyword corresponding to at least one command (e.g., a media playback system command or a smart appliance command).

At block 1114, the method 1100 involves causing one or more device(s) to carry out commands. For example, the satellite may cause a group of one or more playback devices to carry out the at least one first media playback system command. As another example, the satellite may cause a group of one or more smart devices (e.g., smart appliances) to carry out one or more smart device commands. The satellite may cause such devices to carry out the commands by sending data representing instructions to carry out the commands via a suitable interface, such as a network interface.

Turning to FIG. 11B, at block 1116, the method 1200 involves storing, in memory, data representing a second set of local keywords. For instance, a hub device may store data representing local keywords in a library of a local NLU (FIG. 7C). The second set of keywords may, in some aspects, be a superset of the first set of keywords. For instance, the second set of keywords may include the keywords corresponding to the one or more media playback system commands and one or more additional keywords corresponding to one or more additional media playback system commands. The second set of keywords might not necessarily include the context-specific keywords.

At block 1118, the method 1200 involves receiving data representing a first voice input. For instance, the hub device may receive data representing the first voice input from the satellite device. As described above in connection with block 1108 and other examples, the satellite may send such data when falling back to the hub device in the processing of a voice input. The hub device may receive the data representing the first voice input from the satellite device via a network interface over a network (e.g., the LAN 111 in FIG. 1B).

At block 1120, the method 1200 involves processing the first voice input. For instance, the hub device may analyze the captured first voice input using voice analysis components (e.g., the local voice input pipeline 777) and determine that portions of the captured first voice input correspond to words that are in the first set of local keywords. More particularly, the satellite may match such portions of the captured first voice input to keywords in the second set of local keywords with high enough confidence (FIGS. 9A-9D) such that the hub device determines that one or more uttered keywords in the captured first voice input are in the second set of local keywords. The hub device may match portions of the second voice input to at least one particular first keyword corresponding to at least one command (e.g., an additional media playback system command or a smart appliance command).

At block 1122, the method 1100 involves causing one or more device(s) to carry out commands. For example, the hub device may cause a group of one or more playback devices to carry out at least one second media playback system command. The hub device may cause such devices to carry out the commands by sending data representing instructions to carry out the commands via a suitable interface, such as a network interface.

As noted above, in some cases, local processing of a voice input (by a satellite or a hub device) may fall back to the cloud. For instance, the satellite device may capturing an additional voice input and determine that one or more uttered keywords in the captured additional voice input are not in the first set of local keywords stored in the memory of the MCU. The satellite may fall back to the hub device or the cloud by sending the data representing the additional voice input to the hub device or the cloud. If the hub device receives the data representing the additional voice input and is unable to process that input, the hub device in term may fall back to the cloud by sending the data representing the additional voice input to the cloud.

CONCLUSION

The description above discloses, among other things, various example systems, methods, apparatus, and articles of manufacture including, among other components, firmware and/or software executed on hardware. It is understood that such examples are merely illustrative and should not be considered as limiting. For example, it is contemplated that any or all of the firmware, hardware, and/or software aspects or components can be embodied exclusively in hardware, exclusively in software, exclusively in firmware, or in any combination of hardware, software, and/or firmware. Accordingly, the examples provided are not the only way(s) to implement such systems, methods, apparatus, and/or articles of manufacture.

The specification is presented largely in terms of illustrative environments, systems, procedures, steps, logic blocks, processing, and other symbolic representations that directly or indirectly resemble the operations of data processing devices coupled to networks. These process descriptions and representations are typically used by those skilled in the art to most effectively convey the substance of their work to others skilled in the art. Numerous specific details are set forth to provide a thorough understanding of the present disclosure. However, it is understood to those skilled in the art that certain embodiments of the present disclosure can be practiced without certain, specific details. In other instances, well known methods, procedures, components, and circuitry have not been described in detail to avoid unnecessarily obscuring aspects of the embodiments. Accordingly, the scope of the present disclosure is defined by the appended claims rather than the forgoing description of embodiments.

When any of the appended claims are read to cover a purely software and/or firmware implementation, at least one of the elements in at least one example is hereby expressly defined to include a tangible, non-transitory medium such as a memory, DVD, CD, Blu-ray, and so on, storing the software and/or firmware.

The present technology is illustrated, for example, according to various aspects described below. Various examples of aspects of the present technology are described as numbered examples (1, 2, 3, etc.) for convenience. These are provided as examples and do not limit the present technology. It is noted that any of the dependent examples may be combined in any combination, and placed into a respective independent example. The other examples can be presented in a similar manner.

Example 1: A method to be performed by a system comprising a hub device and one or more satellite devices, the method comprising: when detecting a voice utterance, (i) forwarding voice data representing the voice utterance to a cloud-based voice assistant service when operating in a first mode and (ii) forwarding voice data to a hub device when operating in a second mode, wherein the hub device performs local spoken language understanding on the voice input.

Example 2: The method of Example 1, further comprising: when the hub device is not joined to the media playback system, operating in the first mode.

Example 3: The method of Example 1 or 2, further comprising: when the hub device is joined to the media playback system, operating in the second mode.

Example 4: The method of Example 3, further comprising: decoupling from the cloud-based voice assistant service when the hub device is joined to the media playback system.

Example 5: The method of any preceding Example, further comprising: determining an intent of the voice utterance; and when (i) the intent of the utterance has been detected and (ii) the detected intent pertains to the media playback domain, forward voice data representing the voice utterance to the cloud-based voice assistant service.

Example 6: The method of any preceding Example, wherein the satellite devices comprise at least one of: one or more first playback devices or one or more microcontroller units

Example 7: The method of any preceding Example, and wherein the hub device comprises a second playback device.

Example 8: A system configured to perform the method of any of Examples 1-5.

Example 9: A tangible, non-transitory, computer-readable medium having instructions stored thereon that are executable by one or more processors to cause a system to perform the method of any one of Examples 1-5.

Example 10: A satellite device configured to perform the method of any of Examples 1-5.

Example 11: A method to be performed by a system comprising a satellite device and a hub device, the method comprising: storing, in memory of the satellite device, data representing a first set of local keywords comprising (a) first keywords corresponding to one or more media playback system commands and (b) second keywords corresponding to one or more smart appliance commands; capturing a first voice input via at least one first microphone of the satellite device, wherein capturing the first voice input comprises buffering first voice data; determining that one or more uttered keywords in the captured first voice input are not in the first set of local keywords stored in the memory of the satellite device; in response to the determining, sending, via a first network interface of the satellite device, data representing the first voice input to the hub device; capturing a second voice input via the at least one first microphone, wherein capturing the second voice input comprises buffering second voice data; processing the second voice input, wherein processing the second voice input comprises matching portions of the second voice input to at least one particular first keyword corresponding to at least one first media playback system command; causing, via the first network interface, a group of one or more playback devices to carry out the at least one first media playback system command; storing, in memory of the hub device, data representing a second set of local keywords comprising (a) the first keywords and (b) third keywords corresponding to one or more additional media playback system commands; receiving, via a second network interface of the hub device, the data representing the first voice input; processing the first voice input, wherein processing the first voice input comprises matching portions of the first voice input to at least one particular third keyword corresponding to at least one additional media playback system command; and causing, via the second network interface, the group of one or more playback devices to carry out the at least one additional media playback system command.

Example 12: The method of Example 11, wherein the MCU is carried in a smart appliance configured to carry out the one or more smart appliance commands, and wherein the method further comprises: capturing a third voice input via the at least one first microphone, wherein capturing the third voice input comprises buffering third voice data; processing the third voice input, wherein processing the third voice input comprises matching portions of the third voice input to at least one particular first second corresponding to at least one smart appliance command; and causing, via the first network interface, the smart appliance to carry out the at least one smart appliance command.

Example 13: The method of Example 11, wherein the smart appliance comprises a smart illumination device, and wherein causing the smart appliance to carry out the at least one smart appliance command comprise causing the smart illumination device to illuminate.

Example 14: The method of Example 11, wherein the smart appliance comprises a smart kitchen appliance, and wherein causing the smart appliance to carry out the at least one smart appliance command comprise causing the smart kitchen appliance to turn on.

Example 15: The method of any of Examples 11-14, wherein the group of one or more playback devices comprise the playback device and at least one additional playback device, and wherein the second functions further comprise: playing back audio content in synchrony with the at least one additional playback device according to the at least one first media playback system command.

Example 16: The method of any of Examples 11-15, further comprising: capturing a fourth voice input via the at least one first microphone, wherein capturing the fourth voice input comprises buffering fourth voice data; determining that one or more uttered keywords in the captured fourth voice input are not in the first set of local keywords stored in the memory of the MCU; in response to the determining, sending, via the first network interface, data representing the fourth voice input to the playback device; receiving, via the second network interface, the data representing the fourth voice input; determining that one or more uttered keywords in the captured fourth voice input are not in the second set of local keywords stored in the memory of the playback device; and in response to the determining, sending, via the second network interface, additional data representing the fourth voice input to a computing system for processing of the fourth voice input.

Example 17: The method of any of Examples 11-16, further comprising: capturing a fifth voice input via the at least one first microphone, wherein capturing the fifth voice input comprises buffering fifth voice data; determining that (i) one or more uttered keywords in the captured fifth voice input are not in the first set of local keywords stored in the memory of the MCU and (ii) the playback device is not available; and in response to the determining, sending, via the first network interface, additional data representing the fifth voice input to a cloud computing system for processing of the fifth voice input.

Example 18: The method of any of Examples 11-17, further comprising: capturing a sixth voice input via the at least one second microphone, wherein capturing the sixth voice input comprises buffering sixth voice data; processing the sixth voice input, wherein processing the sixth voice input comprises matching portions of the sixth voice input to at least one particular third keyword corresponding to at least one additional media playback system command; and causing, via the second network interface, a group of one or more playback devices to carry out the at least one additional media playback system command.

Example 19: The method of any of Examples 11-18, further comprising: storing, in memory of an additional playback device, data representing a third set of local keywords comprising the first keywords corresponding to one or more media playback system commands; capturing a seventh voice input via at least one third microphone, wherein capturing the seventh voice input comprises buffering seventh voice data; determining that one or more uttered keywords in the captured seventh voice input are not in the third set of local keywords stored in the memory of the additional playback device; and in response to the determining, sending, via the third network interface, data representing the seventh voice input to the playback device for processing of the seventh voice input.

Example 20: The method of any of Examples 11-19, wherein the one or more media playback system commands comprise transport control commands and volume control commands, and wherein the one or more additional media playback system commands comprise playback commands with associated parameters corresponding to audio content metadata.

Example 21: The method of any of Examples 11-20, wherein the satellite device comprises a microcontroller unit, and the hub device comprises a playback device.

Example 22: The method of any of Examples 11-20, wherein the satellite device comprises a first playback device, and the hub device comprises a second playback device.

Example 23: A system configured to perform the method of any of Examples 11-22.

Example 24: A tangible, non-transitory, computer-readable medium having instructions stored thereon that are executable by one or more processors to cause a system to perform the method of any one of Examples 11-22.

Example 25: A device configured to perform the method of any of Examples 11-22. 

We claim:
 1. A system comprising a microcontroller unit (MCU) and a playback device, the MCU comprising: at least one first microphone; a first network interface; at least one first processor; at least one first tangible, non-transitory computer-readable medium; and first program instructions stored on the at least one first tangible, non-transitory computer-readable medium that, when executed by the at least one first processor, cause the MCU to perform first functions comprising: storing, in memory of the MCU, data representing a first set of local keywords comprising (a) first keywords corresponding to one or more media playback system commands and (b) second keywords corresponding to one or more smart appliance commands; capturing a first voice input via the at least one first microphone, wherein capturing the first voice input comprises buffering first voice data; determining that one or more uttered keywords in the captured first voice input are not in the first set of local keywords stored in the memory of the MCU; in response to the determining, sending, via the first network interface, data representing the first voice input to the playback device; capturing a second voice input via the at least one first microphone, wherein capturing the second voice input comprises buffering second voice data; processing the second voice input, wherein processing the second voice input comprises matching portions of the second voice input to at least one particular first keyword corresponding to at least one first media playback system command; and causing, via the first network interface, a group of one or more playback devices to carry out the at least one first media playback system command; and the playback device comprising: at least one second microphone; a second network interface; at least one second processor; at least one second tangible, non-transitory computer-readable medium; and second program instructions stored on the at least one second tangible, non-transitory computer-readable medium that, when executed by the at least one second processor, cause the second playback device to perform second functions comprising: storing, in memory of the playback device, data representing a second set of local keywords comprising (a) the first keywords and (b) third keywords corresponding to one or more additional media playback system commands; receiving, via the second network interface, the data representing the first voice input; processing the first voice input, wherein processing the first voice input comprises matching portions of the first voice input to at least one particular third keyword corresponding to at least one additional media playback system command; and causing, via the second network interface, the group of one or more playback devices to carry out the at least one additional media playback system command.
 2. The system of claim 1, wherein the MCU is carried in a smart appliance configured to carry out the one or more smart appliance commands, and wherein the first functions further comprise: capturing a third voice input via the at least one first microphone, wherein capturing the third voice input comprises buffering third voice data; processing the third voice input, wherein processing the third voice input comprises matching portions of the third voice input to at least one particular first second corresponding to at least one smart appliance command; and causing, via the first network interface, the smart appliance to carry out the at least one smart appliance command.
 3. The system of claim 2, wherein the smart appliance comprises a smart illumination device, and wherein causing the smart appliance to carry out the at least one smart appliance command comprise causing the smart illumination device to illuminate.
 4. The system of claim 2, wherein the smart appliance comprises a smart kitchen appliance, and wherein causing the smart appliance to carry out the at least one smart appliance command comprise causing the smart kitchen appliance to turn on.
 5. The system of claim 1, wherein the group of one or more playback devices comprise the playback device and at least one additional playback device, and wherein the second functions further comprise: playing back audio content in synchrony with the at least one additional playback device according to the at least one first media playback system command.
 6. The system of claim 1, wherein the first functions further comprise: capturing a fourth voice input via the at least one first microphone, wherein capturing the fourth voice input comprises buffering fourth voice data; determining that one or more uttered keywords in the captured fourth voice input are not in the first set of local keywords stored in the memory of the MCU; and in response to the determining, sending, via the first network interface, data representing the fourth voice input to the playback device, and wherein the second functions further comprise: receiving, via the second network interface, the data representing the fourth voice input; determining that one or more uttered keywords in the captured fourth voice input are not in the second set of local keywords stored in the memory of the playback device; and in response to the determining, sending, via the second network interface, additional data representing the fourth voice input to a computing system for processing of the fourth voice input.
 7. The system of claim 1, wherein the first functions further comprise: capturing a fifth voice input via the at least one first microphone, wherein capturing the fifth voice input comprises buffering fifth voice data; determining that (i) one or more uttered keywords in the captured fifth voice input are not in the first set of local keywords stored in the memory of the MCU and (ii) the playback device is not available; and in response to the determining, sending, via the first network interface, additional data representing the fifth voice input to a cloud computing system for processing of the fifth voice input.
 8. The system of claim 1, wherein the second functions further comprise: capturing a sixth voice input via the at least one second microphone, wherein capturing the sixth voice input comprises buffering sixth voice data; processing the sixth voice input, wherein processing the sixth voice input comprises matching portions of the sixth voice input to at least one particular third keyword corresponding to at least one additional media playback system command; and causing, via the second network interface, a group of one or more playback devices to carry out the at least one additional media playback system command.
 9. The system of claim 1, wherein the system further comprises an additional playback device, and wherein the additional playback device comprises: at least one third microphone; a third network interface; at least one third processor; at least one third tangible, non-transitory computer-readable medium; and third program instructions stored on the at least one third tangible, non-transitory computer-readable medium that, when executed by the at least one third processor, cause the additional playback device to perform third functions comprising: storing, in memory of the additional playback device, data representing a third set of local keywords comprising the first keywords corresponding to one or more media playback system commands; capturing a seventh voice input via the at least one third microphone, wherein capturing the seventh voice input comprises buffering seventh voice data; determining that one or more uttered keywords in the captured seventh voice input are not in the third set of local keywords stored in the memory of the additional playback device; and in response to the determining, sending, via the third network interface, data representing the seventh voice input to the playback device for processing of the seventh voice input.
 10. The system of claim 1, wherein the one or more media playback system commands comprise transport control commands and volume control commands, and wherein the one or more additional media playback system commands comprise playback commands with associated parameters corresponding to audio content metadata.
 11. A system comprising a microcontroller unit (MCU), the MCU comprising: at least one microphone; a network interface; at least one processor; at least one tangible, non-transitory computer-readable medium; and program instructions stored on the at least one tangible, non-transitory computer-readable medium that, when executed by the at least one processor, cause the MCU to perform functions comprising: storing, in memory of the MCU, data representing a set of local keywords comprising (a) first keywords corresponding to one or more media playback system commands and (b) second keywords corresponding to one or more smart appliance commands; capturing a first voice input via the at least one microphone, wherein capturing the first voice input comprises buffering first voice data; determining that one or more uttered keywords in the captured first voice input are not in the set of local keywords stored in the memory of the MCU; in response to the determining, sending, via the network interface, data representing the first voice input to a playback device for processing of the first voice input; capturing a second voice input via the at least one microphone, wherein capturing the second voice input comprises buffering second voice data; processing the second voice input, wherein processing the second voice input comprises matching portions of the second voice input to at least one particular first keyword corresponding to at least one first media playback system command; and causing, via the network interface, a group of one or more playback devices to carry out the at least one first media playback system command.
 12. The system of claim 11, wherein the MCU is carried in a smart appliance configured to carry out the one or more smart appliance commands, and wherein the functions further comprise: capturing a third voice input via the at least one microphone, wherein capturing the third voice input comprises buffering third voice data; processing the third voice input, wherein processing the third voice input comprises matching portions of the third voice input to at least one particular first second corresponding to at least one smart appliance command; and causing, via the network interface, the smart appliance to carry out the at least one smart appliance command.
 13. The system of claim 12, wherein the smart appliance comprises a smart illumination device, and wherein causing the smart appliance to carry out the at least one smart appliance command comprise causing the smart illumination device to illuminate.
 14. The system of claim 12, wherein the smart appliance comprises a smart kitchen appliance, and wherein causing the smart appliance to carry out the at least one smart appliance command comprise causing the smart kitchen appliance to turn on.
 15. The system of claim 11, wherein the functions further comprise: capturing a fourth voice input via the at least one microphone, wherein capturing the fourth voice input comprises buffering fourth voice data; determining that (i) one or more uttered keywords in the captured fourth voice input are not in the set of local keywords stored in the memory of the MCU and (ii) the playback device is not available; and in response to the determining, sending, via the network interface, data representing the fourth voice input to a cloud computing system for processing of the fourth voice input.
 16. A system comprising a first playback device and a second playback device, the first playback device comprising: at least one first microphone; a first network interface; at least one first processor; at least one first tangible, non-transitory computer-readable medium; and first program instructions stored on the at least one first tangible, non-transitory computer-readable medium that, when executed by the at least one first processor, cause the first playback device to perform first functions comprising: storing, in memory of the first playback device, data representing a first set of local keywords comprising (a) first keywords corresponding to one or more media playback system commands and (b) second keywords corresponding to one or more contextual commands; capturing a first voice input via the at least one first microphone, wherein capturing the first voice input comprises buffering first voice data; determining that one or more uttered keywords in the captured first voice input are not in the first set of local keywords stored in the memory of the first playback device; in response to the determining, sending, via the first network interface, data representing the first voice input to the second playback device; capturing a second voice input via the at least one first microphone, wherein capturing the second voice input comprises buffering second voice data; processing the second voice input, wherein processing the second voice input comprises matching portions of the second voice input to at least one particular first keyword corresponding to at least one first media playback system command; and causing, via the first network interface, a group of one or more playback devices to carry out the at least one first media playback system command; and the second playback device comprising: at least one second microphone; a second network interface; at least one second processor; at least one second tangible, non-transitory computer-readable medium; and second program instructions stored on the at least one second tangible, non-transitory computer-readable medium that, when executed by the at least one second processor, cause the second playback device to perform second functions comprising: storing, in memory of the second playback device, data representing a second set of local keywords comprising (a) the first keywords and (b) third keywords corresponding to one or more additional media playback system commands; receiving, via the second network interface, the data representing the first voice input; processing the first voice input, wherein processing the first voice input comprises matching portions of the first voice input to at least one particular third keyword corresponding to at least one additional media playback system command; and causing, via the second network interface, the group of one or more playback devices to carry out the at least one additional media playback system command.
 17. The system of claim 16, wherein the group of one or more playback devices comprise the first playback device and at least one additional playback device, and wherein the first functions further comprise: playing back audio content in synchrony with the at least one additional playback device according to the at least one first media playback system command.
 18. The system of claim 16, wherein the first functions further comprise: capturing a fourth voice input via the at least one first microphone, wherein capturing the fourth voice input comprises buffering fourth voice data; determining that one or more uttered keywords in the captured fourth voice input are not in the first set of local keywords stored in the memory of the first playback device; and in response to the determining, sending, via the first network interface, data representing the fourth voice input to the second playback device, and wherein the second functions further comprise: receiving, via the second network interface, the data representing the fourth voice input; determining that one or more uttered keywords in the captured fourth voice input are not in the second set of local keywords stored in the memory of the second playback device; and in response to the determining, sending, via the second network interface, additional data representing the fourth voice input to a computing system for processing of the fourth voice input.
 19. The system of claim 16, wherein the first functions further comprise: capturing a fifth voice input via the at least one first microphone, wherein capturing the fifth voice input comprises buffering fifth voice data; determining that (i) one or more uttered keywords in the captured fifth voice input are not in the first set of local keywords stored in the memory of the first playback device and (ii) the second playback device is not available; and in response to the determining, sending, via the first network interface, additional data representing the fifth voice input to a cloud computing system for processing of the fifth voice input.
 20. The system of claim 16, wherein the second functions further comprise: capturing a sixth voice input via the at least one second microphone, wherein capturing the sixth voice input comprises buffering sixth voice data; processing the sixth voice input, wherein processing the sixth voice input comprises matching portions of the sixth voice input to at least one particular third keyword corresponding to at least one additional media playback system command; and causing, via the second network interface, a group of one or more playback devices to carry out the at least one additional media playback system command. 